[PowerPC]: Don't allow r0 as a target for LD_GOT_TPREL_L/32
Summary:
The linker is free to relax this (relocation R_PPC_GOT_TPREL16)
against R_PPC_TLS, if it sees fit (initial exec to local exec). If r0
is used, this can generate execution-invalid code (converts to 'addi
%rX, %r0, FOO, which translates in PPC-lingo to li %rX, FOO). Forbid
this instead.
This fixes static binaries using locales on FreeBSD/powerpc (tested
on FreeBSD/powerpcspe).
Reviewed By: nemanjai
Differential Revision: https://reviews.llvm.org/D76662
Requested by: jhibbits
MFC after: 6 weeks
X-MFC-With: 358851
6dce2be1c7