Run the vcvars bat file for Tcl/Tk

We appear to need this when using the stand-alone CMake GUI and Visual
Studio.  Not sure how this will work in other environments - we may have
to get smarter about when we do or don't use VCVARS_BAT based on what
CMake environment and/or build tools we are using...

tcl/CMakeLists.txt

@@ -77,8 +77,8 @@ if (ENABLE_TCL)
       PATCH_COMMAND ${PATCH_EXECUTABLE};-E;-p1;${PATCH_OPTIONS};-i;${CMAKE_CURRENT_SOURCE_DIR}/tcl.patch
       CONFIGURE_COMMAND ""
       BINARY_DIR ${TCL_SRC_DIR}/win
-      BUILD_COMMAND nmake -f makefile.vc INSTALLDIR=${CMAKE_BUNDLE_INSTALL_PREFIX} SUFX=
-      INSTALL_COMMAND nmake -f makefile.vc install INSTALLDIR=${CMAKE_BUNDLE_INSTALL_PREFIX} SUFX=
+      BUILD_COMMAND ${VCVARS_BAT} && nmake -f makefile.vc INSTALLDIR=${CMAKE_BUNDLE_INSTALL_PREFIX} SUFX=
+      INSTALL_COMMAND ${VCVARS_BAT} && nmake -f makefile.vc install INSTALLDIR=${CMAKE_BUNDLE_INSTALL_PREFIX} SUFX=
       LOG_BUILD ${EXT_BUILD_QUIET}
       LOG_INSTALL ${EXT_BUILD_QUIET}
       LOG_OUTPUT_ON_FAILURE ${EXT_BUILD_QUIET}

tk/CMakeLists.txt

@@ -62,8 +62,8 @@ if (TK_DO_BUILD)
       PATCH_COMMAND ${PATCH_EXECUTABLE};-E;-p1;${PATCH_OPTIONS};-i;${CMAKE_CURRENT_SOURCE_DIR}/tk.patch
       CONFIGURE_COMMAND ""
       BINARY_DIR ${TK_SRC_DIR}/win
-      BUILD_COMMAND nmake -f makefile.vc INSTALLDIR=${CMAKE_BUNDLE_INSTALL_PREFIX} TCLDIR=${TCL_SRC_DIR} SUFX=
-      INSTALL_COMMAND nmake -f makefile.vc install INSTALLDIR=${CMAKE_BUNDLE_INSTALL_PREFIX} TCLDIR=${TCL_SRC_DIR} SUFX=
+      BUILD_COMMAND ${VCVARS_BAT} && nmake -f makefile.vc INSTALLDIR=${CMAKE_BUNDLE_INSTALL_PREFIX} TCLDIR=${TCL_SRC_DIR} SUFX=
+      INSTALL_COMMAND ${VCVARS_BAT} && nmake -f makefile.vc install INSTALLDIR=${CMAKE_BUNDLE_INSTALL_PREFIX} TCLDIR=${TCL_SRC_DIR} SUFX=
       LOG_BUILD ${EXT_BUILD_QUIET}
       LOG_INSTALL ${EXT_BUILD_QUIET}
       LOG_OUTPUT_ON_FAILURE ${EXT_BUILD_QUIET}