Enable -gcolumn-info by default.

This patch flips the default value for -gcolumn-info to be on by
default. I discussed the rationale and provided compile/size data
in:

http://lists.cs.uiuc.edu/pipermail/llvmdev/2014-June/074290.html

This also updates the documentation and some tests that relied on
the lack of column information. Some tests had column information
in the expected output, but it was wrong (the tsan tests). Others
were using the driver to execute.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@212781 91177308-0d34-0410-b5e6-96231b3b80d8