powerpc: avoid -mno-sched-epilog on GCC 4.9 and newer

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Joel Stanley <joel@jms.id.au>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/Makefile

@@ -165,8 +165,12 @@ CC_FLAGS_FTRACE := -pg
 ifdef CONFIG_MPROFILE_KERNEL
 CC_FLAGS_FTRACE += -mprofile-kernel
 endif
-# Work around a gcc code-gen bug with -fno-omit-frame-pointer.
-CC_FLAGS_FTRACE	+= -mno-sched-epilog
+# Work around gcc code-gen bugs with -pg / -fno-omit-frame-pointer in gcc <= 4.8
+# https://gcc.gnu.org/bugzilla/show_bug.cgi?id=44199
+# https://gcc.gnu.org/bugzilla/show_bug.cgi?id=52828
+ifneq ($(cc-name),clang)
+CC_FLAGS_FTRACE	+= $(call cc-ifversion, -lt, 0409, -mno-sched-epilog)
+endif
 endif
 
 CFLAGS-$(CONFIG_TARGET_CPU_BOOL) += $(call cc-option,-mcpu=$(CONFIG_TARGET_CPU))