[mips][mips64r6] Define _MIPS_FPSET, __mips_fpr, and __mips_nan2008 correctly on MIPS32r6/MIPS64r6

Summary:
This removes the need to pass -mnan=2008 explicitly to be able to compile
the test-suite for MIPS32r6/MIPS64r6.

Differential Revision: http://reviews.llvm.org/D4433


git-svn-id: http://llvm.org/svn/llvm-project/cfe/trunk@212619 91177308-0d34-0410-b5e6-96231b3b80d8
cc1as: consolidate option flags with cc1 and eliminate duplication

The clang -cc1as options are nearly a strict subset of -cc1. Instead of
duplicating the definitions and documentation, let's go ahead and share the
definitions in a similar way the current handling of combined driver and
frontend flags, eliminating some of the vestigial legacy surrounding the
assembler subcommand.

git-svn-id: http://llvm.org/svn/llvm-project/cfe/trunk@212620 91177308-0d34-0410-b5e6-96231b3b80d8
Fix 'source-level' hyphenations

git-svn-id: http://llvm.org/svn/llvm-project/cfe/trunk@212621 91177308-0d34-0410-b5e6-96231b3b80d8
Remove dead code from r212620

git-svn-id: http://llvm.org/svn/llvm-project/cfe/trunk@212622 91177308-0d34-0410-b5e6-96231b3b80d8
Prospective legacy build system fix following r212620

git-svn-id: http://llvm.org/svn/llvm-project/cfe/trunk@212624 91177308-0d34-0410-b5e6-96231b3b80d8
[mips][mips64r6] Implement -mips32r6 and -mips64r6 aliases to -march=mips32r6 and -march=mips64r6

Differential Revision: http://reviews.llvm.org/D4434


git-svn-id: http://llvm.org/svn/llvm-project/cfe/trunk@212625 91177308-0d34-0410-b5e6-96231b3b80d8