Handle new cast kind CK_ZeroToOCLEvent to get rid of warning.
I read up on the implicit conversion from zero to event_t, and event_t is a built-in type/keyword when Clang is run with OpenCL support. Thus, no need for IWYU to do anything special.

git-svn-id: http://include-what-you-use.googlecode.com/svn/trunk@442 812d1f90-f944-d88a-411a-122bdc93e1ea
Remove dead code.

git-svn-id: http://include-what-you-use.googlecode.com/svn/trunk@443 812d1f90-f944-d88a-411a-122bdc93e1ea