api_conv.pl:
------------
Description: used to convert old XCB names in camel case to lower
case names.
Usage:
* for several files:
perl -i xcb/tools/api_conv.pl xcb/tools/constants <file1> <file2> ...
* for a directory:
find dir -name '*.[ch]' -exec perl -i xcb/tools/api_conv.pl xcb/tools/constants {} +