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 {} +