libast: cleanup: remove unused/obsolete get* functions

src/lib/libast/comp/{getlogin.c,getpgrp.c}:
- Removed. These functions have been in POSIX for decades so their
  fallbacks are never used on non-museum systems.

src/lib/libast/comp/getdate.c:
- Removed. These unconditionally overrode the OS implementations,
  but they are unused in the AT&T AST code base (2016) and in ours.

src/lib/libast/comp/{getopt.{c,h},getsubopt.c,getoptl.c},
src/lib/libast/include/ast_getopt.h:
- Removed. These reimplementations of POSIX getopt(3) and GNU
  getopt_long(3) were unused in the AT&T AST code base and in ours.

src/lib/libast/comp/getwd.c:
- Removed. Unused and obsoleted by getcwd(3) a long time ago.

src/lib/libast/comp/getgroups.c, src/lib/libast/features/botch.c:
- Removed. getgroups(2) did not have a full AST fallback, but some
  tests for system-specific getgroups bugs (in botch.c, results
  installed in ast_botch.h) with workarounds (in getgroups.c),
  which has been present since 1995 and unchanged since 1998. The
  systems where these bugs were present are not documented, but
  it's a quarter century later, and I've never seen these bugs
  detected on any system I've tested, so it seems safe to assume we
  don't need this any more.

src/cmd/INIT/mamake.c

@@ -329,10 +329,6 @@ extern char		**environ;
 
 #if !_PACKAGE_ast
 
-#if defined(NeXT) || defined(__NeXT)
-#define getcwd(a,b)	getwd(a)
-#endif
-
 /*
  * emit usage message and exit
  */

src/lib/libast/Mamfile

@@ -255,17 +255,6 @@ make install virtual
 		exec - cp -f ${<} ${@}
 	done
 
-	make ast_botch.h implicit
-		make FEATURE/botch
-			make features/botch.c
-				prev FEATURE/sys
-				prev FEATURE/lib
-			done
-			exec - invoke_iffe ${<} -I. -Icomp -Iinclude -Istd
-		done
-		exec - cp -f ${<} ${@}
-	done
-
 	make ast_wchar.h implicit
 		make FEATURE/wchar
 			prev std/wctype.h implicit
@@ -342,9 +331,6 @@ make install virtual
 				prev FEATURE/common
 				prev FEATURE/lib
 				prev FEATURE/standards
-				make comp/getopt.h implicit
-					prev include/ast_getopt.h implicit
-				done
 				make conflim.h implicit
 					prev FEATURE/standards
 					prev FEATURE/common
@@ -378,12 +364,9 @@ make install virtual
 				prev ast_wchar.h
 				prev ast_common.h
 			done
-			prev comp/getopt.h
 			prev ast_map.h
-			prev ast_botch.h
 			prev ast_limits.h
 			prev ast_fcntl.h
-			prev include/ast_getopt.h
 			prev ast_sys.h
 			prev ast_lib.h
 			prev ast_common.h
@@ -2620,13 +2603,6 @@ make install virtual
 			exec - compile ${<}
 		done
 
-		make getlogin.o
-			make comp/getlogin.c
-				prev include/ast.h
-			done
-			exec - compile ${<}
-		done
-
 		make putenv.o
 			make comp/putenv.c
 				prev ast_map.h
@@ -2704,13 +2680,6 @@ make install virtual
 			exec - compile ${<}
 		done
 
-		make getpgrp.o
-			make comp/getpgrp.c
-				prev include/ast_std.h
-			done
-			exec - compile ${<}
-		done
-
 		make setpgid.o
 			make comp/setpgid.c
 				prev include/error.h
@@ -2766,13 +2735,6 @@ make install virtual
 			exec - compile ${<} -Idir
 		done
 
-		make getwd.o
-			make comp/getwd.c
-				prev include/ast.h
-			done
-			exec - compile ${<}
-		done
-
 		make dup2.o
 			make comp/dup2.c
 				prev include/error.h
@@ -2788,14 +2750,6 @@ make install virtual
 			exec - compile ${<}
 		done
 
-		make getgroups.o
-			make comp/getgroups.c
-				prev include/error.h
-				prev include/ast.h
-			done
-			exec - compile ${<}
-		done
-
 		make mount.o
 			make comp/mount.c
 				prev include/error.h
@@ -2986,23 +2940,6 @@ make install virtual
 			exec - compile ${<}
 		done
 
-		make getdate.o
-			make comp/getdate.c
-				prev ast_map.h
-				prev include/tm.h
-				prev include/ast.h
-			done
-			exec - compile ${<}
-		done
-
-		make getsubopt.o
-			make comp/getsubopt.c
-				prev include/error.h
-				prev include/ast.h
-			done
-			exec - compile ${<}
-		done
-
 		make glob.o
 			make misc/glob.c
 				prev include/glob.h implicit
@@ -4632,26 +4569,6 @@ make install virtual
 			exec - compile ${<}
 		done
 
-		make getopt.o
-			make comp/getopt.c
-				prev include/option.h
-				prev include/error.h
-				prev include/ast.h
-			done
-			exec - compile ${<}
-		done
-
-		make getoptl.o
-			make comp/getoptl.c
-				prev comp/getopt.h
-				prev include/option.h
-				prev include/error.h
-				prev include/ast_getopt.h
-				prev include/ast.h
-			done
-			exec - compile ${<}
-		done
-
 		make aso.o
 			make aso/aso.c
 				prev std/stdio.h
@@ -4926,14 +4843,14 @@ make install virtual
 	note * #include headers
 	make ${INSTALLROOT}/lib/mam/ast
 		note * ...main AST headers
-		loop HDR ast ast_dir ast_getopt ast_std ast_windows ccode cdt cmdarg debug dt error find ftwalk fts glob hash hashkey hashpart ip6 ls magic mc mime mnt modecanon modex namval option proc recfmt regex sfio sfio_s sfio_t sfdisc shcmd stk stak swap tar times tm tok usage vdb vmalloc wait magicid fnv aso
+		loop HDR ast ast_dir ast_std ast_windows ccode cdt cmdarg debug dt error find ftwalk fts glob hash hashkey hashpart ip6 ls magic mc mime mnt modecanon modex namval option proc recfmt regex sfio sfio_s sfio_t sfdisc shcmd stk stak swap tar times tm tok usage vdb vmalloc wait magicid fnv aso
 			make ${INCLUDE_AST}/${HDR}.h
 				prev include/${HDR}.h
 				exec - cp -f ${<} ${@}
 			done
 		done
 		note * ...comp(atibility)
-		loop HDR ftw getopt re_comp regexp wordexp fnmatch
+		loop HDR ftw re_comp regexp wordexp fnmatch
 			make ${INCLUDE_AST}/${HDR}.h
 				prev comp/${HDR}.h
 				exec - cp -f ${<} ${@}
@@ -4947,7 +4864,7 @@ make install virtual
 			done
 		done
 		note * ...generated headers
-		loop HDR releaseflags ast_standards ast_common ast_lib ast_sys lc align sig tmx tv ast_api ast_botch ast_ccode ast_fcntl ast_float ast_fs ast_map ast_mmap ast_mode ast_ndbm ast_param ast_random ast_time ast_tty ast_wait ast_limits ast_sizeof ast_dirent ast_iconv ast_nl_types ast_stdio ast_wchar ast_wctype
+		loop HDR releaseflags ast_standards ast_common ast_lib ast_sys lc align sig tmx tv ast_api ast_ccode ast_fcntl ast_float ast_fs ast_map ast_mmap ast_mode ast_ndbm ast_param ast_random ast_time ast_tty ast_wait ast_limits ast_sizeof ast_dirent ast_iconv ast_nl_types ast_stdio ast_wchar ast_wctype
 			make ${INCLUDE_AST}/${HDR}.h
 				prev ${HDR}.h
 				exec - cp -f ${<} ${@}