AndroidKernel.mk: Pass -mno-android to gcc if supported

When using a cross compiler that supports both Android
and non-Android configurations, pass the -mno-android flag
to use non-Android spec to compile the kernel.

Change-Id: Ibd952f3aea06f9f4f8c957c8e2a7666dd5dcdbba
Signed-off-by: David Ng <dave@codeaurora.org>

AndroidKernel.mk

@@ -42,6 +42,11 @@ endif
 
 ifeq ($(TARGET_PREBUILT_KERNEL),)
 
+KERNEL_GCC_NOANDROID_CHK := $(shell (echo "int main() {return 0;}" | $(KERNEL_CROSS_COMPILE)gcc -E -mno-android - > /dev/null 2>&1 ; echo $$?))
+ifeq ($(strip $(KERNEL_GCC_NOANDROID_CHK)),0)
+KERNEL_CFLAGS := KCFLAGS=-mno-android
+endif
+
 KERNEL_OUT := $(TARGET_OUT_INTERMEDIATES)/KERNEL_OBJ
 KERNEL_CONFIG := $(KERNEL_OUT)/.config
 
@@ -96,8 +101,8 @@ $(KERNEL_CONFIG): $(KERNEL_OUT)
 $(TARGET_PREBUILT_INT_KERNEL): $(KERNEL_OUT) $(KERNEL_HEADERS_INSTALL)
 	$(hide) echo "Building kernel..."
 	$(hide) rm -rf $(KERNEL_OUT)/arch/$(KERNEL_ARCH)/boot/dts
-	$(MAKE) -C kernel O=../$(KERNEL_OUT) ARCH=$(KERNEL_ARCH) CROSS_COMPILE=$(KERNEL_CROSS_COMPILE)
-	$(MAKE) -C kernel O=../$(KERNEL_OUT) ARCH=$(KERNEL_ARCH) CROSS_COMPILE=$(KERNEL_CROSS_COMPILE) modules
+	$(MAKE) -C kernel O=../$(KERNEL_OUT) ARCH=$(KERNEL_ARCH) CROSS_COMPILE=$(KERNEL_CROSS_COMPILE) $(KERNEL_CFLAGS)
+	$(MAKE) -C kernel O=../$(KERNEL_OUT) ARCH=$(KERNEL_ARCH) CROSS_COMPILE=$(KERNEL_CROSS_COMPILE) $(KERNEL_CFLAGS) modules
 	$(MAKE) -C kernel O=../$(KERNEL_OUT) INSTALL_MOD_PATH=../../$(KERNEL_MODULES_INSTALL) INSTALL_MOD_STRIP=1 ARCH=$(KERNEL_ARCH) CROSS_COMPILE=$(KERNEL_CROSS_COMPILE) modules_install
 	$(mv-modules)
 	$(clean-module-folder)