kbuild: gcov: enable -fno-tree-loop-im if supported

Clang does not recognize this compiler option.

Reported-by: Prasad Sodagudi <psodagud@codeaurora.org>
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
diff --git a/Makefile b/Makefile
index d0d2652..ba09085 100644
--- a/Makefile
+++ b/Makefile
@@ -623,7 +623,9 @@
 
 KBUILD_CFLAGS	+= $(call cc-option,-fno-PIE)
 KBUILD_AFLAGS	+= $(call cc-option,-fno-PIE)
-CFLAGS_GCOV	:= -fprofile-arcs -ftest-coverage -fno-tree-loop-im $(call cc-disable-warning,maybe-uninitialized,)
+CFLAGS_GCOV	:= -fprofile-arcs -ftest-coverage \
+	$(call cc-option,-fno-tree-loop-im) \
+	$(call cc-disable-warning,maybe-uninitialized,)
 export CFLAGS_GCOV CFLAGS_KCOV
 
 # The arch Makefile can set ARCH_{CPP,A,C}FLAGS to override the default