To improve consistency and avoid unneeded shell feature (output
redirection).
While here, make other changes to improve consistency
--docnum 1 => --docnum=1
-docnum=x => --docnum=x
This creates the next subfolders in the test directory:
"COFF", "ELF", "MachO", "wasm".
I've also removed platform specific prefixes, like "coff-*".
One unused binary was removed as well: `Inputs/relocs.obj.elf-mips`
Differential revision: https://reviews.llvm.org/D71203