Driver: pass along [-]-[no]compress-debug-sections unfiltered

Rather than validating the flags, pass them through without any
validation.  Arguments passed via -Wa or -Xassembler are passed directly
to the assembler without validation.  The validation was previously
required since we did not provide proper driver level support for
controlling the debug compression on ELF targets.  A subsequent change
will add support for the `-gz` and `-gz=` flags which provide proper
driver level control of the ELF compressed debug sections.

llvm-svn: 305164