Changed syntax of test for -fvtable-thunks so it works.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@17077 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/makeg95.env

@@ -63,7 +63,11 @@ endif
 
 ifeq ($(MINGW32),1)
   ifneq "$(_GCC295)$(_GCC3)" ""
-    CC = gcc --pipe $(if $(_GCC3), , -fvtable-thunks)
+    ifeq ($(_GCC3),1)
+      CC = gcc --pipe
+    else
+      CC = gcc --pipe -fvtable-thunks
+    endif
   else
     CC = gcc
   endif