kernel: filter -no-plt from KCFLAGS

Compiler option -no-plt will break kernel builds on some architectures
eg. (x86)  Filter this option from the recently introduced handling of
KCFLAGS vs EXTRA_OPTIMISATION

Fixes: 1d42af720c6b ("kernel: use KCFLAGS for passing EXTRA_OPTIMIZATION flags")

Suggested-by: Felix Fietkau <[email protected]>

Signed-off-by: Kevin Darbyshire-Bryant <[email protected]>

include/kernel.mk

@@ -101,7 +101,7 @@ endif
 KERNEL_MAKE = $(MAKE) $(KERNEL_MAKEOPTS)
 
 KERNEL_MAKE_FLAGS = \
-	KCFLAGS="$(call iremap,$(BUILD_DIR),$(notdir $(BUILD_DIR))) $(call qstrip,$(CONFIG_EXTRA_OPTIMIZATION)) $(call qstrip,$(CONFIG_KERNEL_CFLAGS))" \
+	KCFLAGS="$(call iremap,$(BUILD_DIR),$(notdir $(BUILD_DIR))) $(filter-out -fno-plt,$(call qstrip,$(CONFIG_EXTRA_OPTIMIZATION))) $(call qstrip,$(CONFIG_KERNEL_CFLAGS))" \
 	HOSTCFLAGS="$(HOST_CFLAGS) -Wall -Wmissing-prototypes -Wstrict-prototypes" \
 	CROSS_COMPILE="$(KERNEL_CROSS)" \
 	ARCH="$(LINUX_KARCH)" \

rules.mk

@@ -62,7 +62,6 @@ ARCH_PACKAGES:=$(call qstrip,$(CONFIG_TARGET_ARCH_PACKAGES))
 BOARD:=$(call qstrip,$(CONFIG_TARGET_BOARD))
 SUBTARGET:=$(call qstrip,$(CONFIG_TARGET_SUBTARGET))
 TARGET_OPTIMIZATION:=$(call qstrip,$(CONFIG_TARGET_OPTIMIZATION))
-export EXTRA_OPTIMIZATION:=$(filter-out -fno-plt,$(call qstrip,$(CONFIG_EXTRA_OPTIMIZATION)))
 TARGET_SUFFIX=$(call qstrip,$(CONFIG_TARGET_SUFFIX))
 BUILD_SUFFIX:=$(call qstrip,$(CONFIG_BUILD_SUFFIX))
 SUBDIR:=$(patsubst $(TOPDIR)/%,%,${CURDIR})