8022617: Openjdk hotspot build is broken on BSD platforms using gcc

Summary: Enforce of preprocessing of all assembly sources by assembler-with-cpp
Reviewed-by: dholmes, erikj

make/bsd/makefiles/gcc.make

@@ -80,7 +80,7 @@ ifeq ($(SPEC),)
     HOSTCC  = $(CC)
   endif
 
-  AS   = $(CC) -c -x assembler-with-cpp
+  AS   = $(CC) -c 
 endif
 
 
@@ -347,6 +347,13 @@ ifeq ($(OS_VENDOR), Darwin)
   LDFLAGS += -mmacosx-version-min=$(MACOSX_VERSION_MIN)
 endif
 
+
+#------------------------------------------------------------------------
+# Assembler flags
+
+# Enforce prerpocessing of .s files
+ASFLAGS += -x assembler-with-cpp
+
 #------------------------------------------------------------------------
 # Linker flags