Add clang-format configuration file.

git-svn-id: http://include-what-you-use.googlecode.com/svn/trunk@554 812d1f90-f944-d88a-411a-122bdc93e1ea
Disallow short block collapsing in .clang-format. Typical style seems to be hanging indent for one-line ifs and many debuggers can't set breakpoints on indivudual statements in one-liners.

git-svn-id: http://include-what-you-use.googlecode.com/svn/trunk@555 812d1f90-f944-d88a-411a-122bdc93e1ea