klibc: Pass -fno-builtin-bcmp with musl/clang combo

clang would emit bcmp built-in for musl bases system
but here we do not link in musl C library, so its best
to disable it

Fixes
git/usr/klibc/memmem.c:38: undefined reference to `bcmp'

Signed-off-by: Khem Raj <raj.khem@gmail.com>
Cc: Andrea Adami <andrea.adami@gmail.com>
(cherry picked from commit 11bc2775af3e47399ac268a2e6fbd63185e478ef)
Signed-off-by: Armin Kuster <akuster808@gmail.com>

meta-initramfs/recipes-devtools/klibc/klibc.inc

@@ -33,6 +33,9 @@ ARMPATCHES_arm = "file://klibc-config-eabi.patch \
 
 S = "${WORKDIR}/git"
 
+OPTFLAGS = "${TUNE_CCARGS} -Os"
+OPTFLAGS_append_libc-musl_toolchain-clang = " -fno-builtin-bcmp"
+
 PARALLEL_MAKE = ""
 EXTRA_OEMAKE = "'KLIBCARCH=${KLIBC_ARCH}' \
                 'CROSS_COMPILE=${TARGET_PREFIX}' \
@@ -43,7 +46,7 @@ EXTRA_OEMAKE = "'KLIBCARCH=${KLIBC_ARCH}' \
                 'INSTALLDIR=${libdir}/klibc' \
                 'SHLIBDIR=${libdir}' \
                 '${KLIBCTHUMB}' \
-                'KLIBCOPTFLAGS=${TUNE_CCARGS} -Os' \
+                'KLIBCOPTFLAGS=${OPTFLAGS}' \
                  V=1 \
                 "