Modify get_reloc_section for targets that map .got.plt to .got

Modify get_reloc_section for targets that map .got.plt to .got

Fixes tic6x testsuite failures due to .rela.plt having a zero sh_info.
I considered passing link_info to get_reloc_section so we could
directly return the .got.plt output section, but we need the fallback
to name lookup anyway for objcopy.

bfd/
	* elf.c (_bfd_elf_get_reloc_section): Allow for .got.plt being
	mapped to output .got section.
ld/testsuite/
	* ld-arm/tls-gdesc-nlazy.g: Adjust for readelf note.
	* ld-tic6x/shlib-1.rd: Expect corrected .rela.plt sh_info.
	* ld-tic6x/shlib-1b.rd: Likewise.
	* ld-tic6x/shlib-1r.rd: Likewise.
	* ld-tic6x/shlib-1rb.rd: Likewise.
	* ld-tic6x/shlib-app-1.rd: Likewise.
	* ld-tic6x/shlib-app-1b.rd: Likewise.
	* ld-tic6x/shlib-app-1r.rd: Likewise.
	* ld-tic6x/shlib-app-1rb.rd: Likewise.
	* ld-tic6x/shlib-noindex.rd: Likewise.