[GCC]: Fix fence.i bug (#296)

There are many issues: 260, 285, 287 has to be solved

This workaround helps to add neccessary zicsr and
zifencei for cssr and fence.i accordingly.

Makefile.in

@@ -57,16 +57,27 @@ endif
 # *** If --with-abi is given but --with-arch is not, then the ISA uses the
 #     compiler's default.
 
+
+ifneq (@WITH_ARCH@,)
+  is_32bit := $(findstring 32,@WITH_ARCH@)
+else
+ifneq (@host_alias@,)
+	is_32bit := $(findstring 32,@host_alias@)
+else
+	is_32bit := ""
+endif
+endif
+
 ifneq (@WITH_ARCH@,)
   march := -march=@WITH_ARCH@
-  is_32bit := $(findstring 32,$(march))
-  ifeq (@WITH_ABI@,)
-    mabi := -mabi=$(if $(is_32bit),ilp32,lp64)
-  endif
+else
+	march := -march=$(if $(is_32bit),rv32,rv64)im_zicsr_zifencei
 endif
 
 ifneq (@WITH_ABI@,)
   mabi := -mabi=@WITH_ABI@
+else
+  mabi := -mabi=$(if $(is_32bit),ilp32,lp64)
 endif
 
 # Installation directories