Limit -maltivec to specific source files on OpenBSD too (untested)

Makefile

@@ -770,11 +770,11 @@ ifeq ($(PLATFORM),openbsd)
     HAVE_VM_COMPILED=true
   else
   ifeq ($(ARCH),ppc)
-    BASE_CFLAGS += -maltivec
+    ALTIVEC_CFLAGS = -maltivec
     HAVE_VM_COMPILED=true
   endif
   ifeq ($(ARCH),ppc64)
-    BASE_CFLAGS += -maltivec
+    ALTIVEC_CFLAGS = -maltivec
     HAVE_VM_COMPILED=true
   endif
   ifeq ($(ARCH),sparc64)