glretrace: Properly interpret CGLSetSurface and CGLClearDrawable calls.
apitrace-get-counts: Filter out lines that don't match regex

Lines that matched the regex for GL function calls, sed correctly
replaced the line with just the function name. However, lines that did
not match the regex, sed passed the lines through unchanged.

Use `sed -n` to suppress printing unmatching lines.
Merge branch 'master' of git://github.com/apitrace/apitrace