x86/boot: do not create unwind tables

This way .eh_frame section is not included in *.lnk and *.bin files.
Hence, final e.g. reloc.bin file size is reduced from 408 bytes to
272 bytes and it contains only used code and data.

Suggested-by: Jan Beulich <jbeulich@suse.com>
Signed-off-by: Daniel Kiper <daniel.kiper@oracle.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>

xen/arch/x86/boot/build32.mk

@@ -4,7 +4,7 @@ include $(XEN_ROOT)/Config.mk
 
 $(call cc-options-add,CFLAGS,CC,$(EMBEDDED_EXTRA_CFLAGS))
 
-CFLAGS += -Werror -fno-builtin -msoft-float
+CFLAGS += -Werror -fno-asynchronous-unwind-tables -fno-builtin -msoft-float
 CFLAGS := $(filter-out -flto,$(CFLAGS)) 
 
 # NB. awk invocation is a portable alternative to 'head -n -1'