[csmith-project/creduce] 9a5880: Filter more problematic options out of `LLVMCXXFLA...

[Eric Eide <eeide@cs.utah.edu>]

  Branch: refs/heads/master
  Home:   https://github.com/csmith-project/creduce
  Commit: 9a588081dd3b08e0ec70469a376e17a011c5e561
      https://github.com/csmith-project/creduce/commit/9a588081dd3b08e0ec70469a376e17a011c5e561
  Author: Eric Eide <eeide@cs.utah.edu>
  Date:   2016-03-16 (Wed, 16 Mar 2016)

  Changed paths:
    M clang_delta/Makefile.am
    M clang_delta/Makefile.in
    M configure
    M m4/ax_llvm.m4

  Log Message:
  -----------
  Filter more problematic options out of `LLVMCXXFLAGS`.

Yang Chen reports that if you build Clang 3.8.0 with Clang, you end up
with `-fcolor-diagnostics` in the output of `llvm-config --cxxflags`.
This is a problem if you later try to build C-Reduce with GCC, because
GCC doesn't grok that flag.

With this commit, we now try to filter most diagnostics-reporting
options out of `llvm-config --cxxflags`.  There are a few that we still
do not match --- for example, Clang's `-fansi-escape-codes` and GCC's
`-fmessage-length` --- but I expect that these are rare enough that we
won't be troubled by them in practice.