[ClusterLabs/libqb] 5279aa: Fix detection of warning flags for clang

[David Vossel]

  Branch: refs/heads/master
  Home:   https://github.com/ClusterLabs/libqb
  Commit: 5279aa3b5ffe60010f9a29a6db98ba0f4cd292c3
     
https://github.com/ClusterLabs/libqb/commit/5279aa3b5ffe60010f9a29a6db98b...
  Author: Ruben Kerkhof <ruben(a)rubenkerkhof.com&gt;
  Date:   2015-01-19 (Mon, 19 Jan 2015)

  Changed paths:
    M configure.ac

  Log Message:
  -----------
  Fix detection of warning flags for clang

Using ./configure CC=clang, the following flags are detected
as supported:

checking whether clang supports "-Wgnu89-inline"... yes
checking whether clang supports "-Wno-strict-aliasing"... yes

Which results in a lot of warnings during make:

warning: unknown warning option '-Wunsigned-char' [-Wunknown-warning-option]
warning: unknown warning option '-Wgnu89-inline' [-Wunknown-warning-option]

Clang doesn't support these flags, but the compile check returns a
warning, not an error:

configure:16649: checking whether clang supports "-Wunsigned-char"
configure:16662: clang -E  -Wunsigned-char conftest.c
warning: unknown warning option '-Wunsigned-char' [-Wunknown-warning-option]
1 warning generated.
configure:16662: $? = 0
configure:16663: result: yes


  Commit: fb664811105afff66f48f214d5d0b82a1e1c0bee
     
https://github.com/ClusterLabs/libqb/commit/fb664811105afff66f48f214d5d0b...
  Author: David Vossel <dvossel(a)redhat.com&gt;
  Date:   2015-01-20 (Tue, 20 Jan 2015)

  Changed paths:
    M configure.ac

  Log Message:
  -----------
  Merge pull request #137 from rubenk/detect-warning-flags-better

Fix detection of warning flags for clang


Compare: https://github.com/ClusterLabs/libqb/compare/9e8d0e6e4326...fb664811105a