[PATCH] Arm64: fix build with gcc 10

[Jan Beulich <jbeulich@xxxxxxxx>]

With gcc10 inlining is (no longer?) the default for certain atomics.

Suggested-by: Julien Grall <jgrall@xxxxxxxxxx>
Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>

--- a/xen/arch/arm/arch.mk
+++ b/xen/arch/arm/arch.mk
@@ -12,6 +12,7 @@ CFLAGS-$(CONFIG_ARM_32) += -mcpu=cortex-
 
 CFLAGS-$(CONFIG_ARM_64) += -mcpu=generic
 CFLAGS-$(CONFIG_ARM_64) += -mgeneral-regs-only # No fp registers etc
+$(call cc-option-add,CFLAGS-$(CONFIG_ARM_64),CC,-mno-outline-atomics)
 
 ifneq ($(filter command line environment,$(origin CONFIG_EARLY_PRINTK)),)
     $(error You must use 'make menuconfig' to enable/disable early printk now)