x86/EFI: work around GNU ld 2.36 issue

Our linker capability check fails with the recent binutils release's ld:

.../check.o:(.debug_aranges+0x6): relocation truncated to fit: R_X86_64_32 against `.debug_info'
.../check.o:(.debug_info+0x6): relocation truncated to fit: R_X86_64_32 against `.debug_abbrev'
.../check.o:(.debug_info+0xc): relocation truncated to fit: R_X86_64_32 against `.debug_str'+76
.../check.o:(.debug_info+0x11): relocation truncated to fit: R_X86_64_32 against `.debug_str'+d
.../check.o:(.debug_info+0x15): relocation truncated to fit: R_X86_64_32 against `.debug_str'+2b
.../check.o:(.debug_info+0x29): relocation truncated to fit: R_X86_64_32 against `.debug_line'
.../check.o:(.debug_info+0x30): relocation truncated to fit: R_X86_64_32 against `.debug_str'+19
.../check.o:(.debug_info+0x37): relocation truncated to fit: R_X86_64_32 against `.debug_str'+71
.../check.o:(.debug_info+0x3e): relocation truncated to fit: R_X86_64_32 against `.debug_str'
.../check.o:(.debug_info+0x45): relocation truncated to fit: R_X86_64_32 against `.debug_str'+5e
.../check.o:(.debug_info+0x4c): additional relocation overflows omitted from the output

Tell the linker to strip debug info as a workaround. Debug info has been
getting stripped already anyway when linking the actual xen.efi.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>
master commit: f4318db940
master date: 2021-02-05 14:09:42 +0100

xen/arch/x86/Makefile

@@ -173,7 +173,7 @@ EFI_LDFLAGS += --major-subsystem-version=2 --minor-subsystem-version=0
 # Check if the compiler supports the MS ABI.
 export XEN_BUILD_EFI := $(shell $(CC) $(filter-out $(CFLAGS-y) .%.d,$(CFLAGS)) -c efi/check.c -o efi/check.o 2>/dev/null && echo y)
 # Check if the linker supports PE.
-XEN_BUILD_PE := $(if $(XEN_BUILD_EFI),$(shell $(LD) -mi386pep --subsystem=10 -o efi/check.efi efi/check.o 2>/dev/null && echo y))
+XEN_BUILD_PE := $(if $(XEN_BUILD_EFI),$(shell $(LD) -mi386pep --subsystem=10 -S -o efi/check.efi efi/check.o 2>/dev/null && echo y))
 CFLAGS-$(XEN_BUILD_EFI) += -DXEN_BUILD_EFI
 
 $(TARGET).efi: VIRT_BASE = 0x$(shell $(NM) efi/relocs-dummy.o | sed -n 's, A VIRT_START$$,,p')