Copy binutils change from CHERIBSD:
https://github.com/CTSRD-CHERI/cheribsd/commit/85ff1bcfc56c82334e50835ba3694e3fb17594ba

Implement support for R_MIPS_PC32 by copying the code in elf32-mips.c to
elf64-mips.c.

From examining other relocations, no other changes appear to be required,
but I'm not sure how to test the result. It is sufficient to allow code
where llvm produces R_MIPS_PC32 relocations to link (or since such code
is mostly threaded, to fail due to missing jemalloc symbols rather than
linker errors).

Submitted by: brooks