Clean up IWYU header mappings.  No functional change intended.

git-svn-id: http://include-what-you-use.googlecode.com/svn/trunk@542 812d1f90-f944-d88a-411a-122bdc93e1ea
Update GNU libc file mappings (issue #131).

git-svn-id: http://include-what-you-use.googlecode.com/svn/trunk@543 812d1f90-f944-d88a-411a-122bdc93e1ea
Tell MSVC STL not to use exceptions. Suppresses warnings.

git-svn-id: http://include-what-you-use.googlecode.com/svn/trunk@544 812d1f90-f944-d88a-411a-122bdc93e1ea