MIPS VDSO is not built when using LLD

[tpimh]

When using lld to link MIPS kernel, the following warning is triggered:

arch/mips/vdso/Makefile:62: MIPS VDSO requires binutils >= 2.25

With with this segment removed, VDSO is built:

linux/arch/mips/vdso/Makefile

Lines 50 to 66 in dcf78ee

	#
	# For the pre-R6 code in arch/mips/vdso/vdso.h for locating
	# the base address of VDSO, the linker will emit a R_MIPS_PC32
	# relocation in binutils > 2.25 but it will fail with older versions
	# because that relocation is not supported for that symbol. As a result
	# of which we are forced to disable the VDSO symbols when building
	# with < 2.25 binutils on pre-R6 kernels. For more references on why we
	# can't use other methods to get the base address of VDSO please refer to
	# the comments on that file.
	#
	ifndef CONFIG_CPU_MIPSR6
	ifeq ($(call ld-ifversion, -lt, 225000000, y),y)
	$(warning MIPS VDSO requires binutils >= 2.25)
	obj-vdso-y := $(filter-out vgettimeofday.o, $(obj-vdso-y))
	ccflags-vdso += -DDISABLE_MIPS_VDSO
	endif
	endif

R_MIPS_PC32 relocation is supported by LLD: https://reviews.llvm.org/rLLD259782.

[nathanchance]

samitolvanen@44939ce would solve this so we could just exclude this entire block if using LLD.

[nathanchance]

Patch sent: https://lore.kernel.org/lkml/20200419180445.26722-2-natechancellor@gmail.com/

[nathanchance]

v2: https://lore.kernel.org/lkml/20200419202128.20571-1-natechancellor@gmail.com/