cmd/link: add relocs type for mips64x

cmd/link: add relocs type for mips64x

The race detector of llvm adds four reloc types even with -fPIC

elf.R_MIPS_CALL16
elf.R_MIPS_GPREL32
elf.R_MIPS_64
elf.R_MIPS_GOT_DISP

Change-Id: If73119dcba14ef74395273eb680f52a0aa853217
Reviewed-on: https://go-review.googlesource.com/c/go/+/270297
Trust: Meng Zhuo <mzh@golangcn.org>
Run-TryBot: Meng Zhuo <mzh@golangcn.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Go Bot <gobot@golang.org>