optee-client: Disable Werror with clang

Main flags are using gcc specific warning options e.g.
-Wunsafe-loop-optimizations which are unkown to clang so it reports then
under -Wunknown-warning-option as an error when -Werror is on

Signed-off-by: Khem Raj <raj.khem@gmail.com>
Signed-off-by: Jon Mason <jon.mason@arm.com>

meta-arm/recipes-security/optee/optee-client.inc

@@ -16,6 +16,7 @@ SRC_URI = " \
 S = "${WORKDIR}/git"
 
 EXTRA_OECMAKE = "-DBUILD_SHARED_LIBS=ON"
+EXTRA_OECMAKE_append_toolchain-clang = " -DCFG_WERROR=0"
 
 do_install_append() {
     install -D -p -m0644 ${WORKDIR}/tee-supplicant.service ${D}${systemd_system_unitdir}/tee-supplicant.service