ftrace: allow architectures to specify ftrace compile options

If the kernel is compiled with function tracer support the -pg compile option
is passed to gcc to generate extra code into the prologue of each function.

This patch replaces the "open-coded" -pg compile flag with a CC_FLAGS_FTRACE
makefile variable which architectures can override if a different option
should be used for code generation.

Acked-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index 649ce68..01df30a 100644
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -234,8 +234,9 @@
 	"$(if $(part-of-module),1,0)" "$(@)";
 recordmcount_source := $(srctree)/scripts/recordmcount.pl
 endif
-cmd_record_mcount = 						\
-	if [ "$(findstring -pg,$(_c_flags))" = "-pg" ]; then	\
+cmd_record_mcount =						\
+	if [ "$(findstring $(CC_FLAGS_FTRACE),$(_c_flags))" =	\
+	     "$(CC_FLAGS_FTRACE)" ]; then			\
 		$(sub_cmd_record_mcount)			\
 	fi;
 endif