Fix help message of apinames. * src/tools/apinames.c: The first header file must be given after the options. All arguments after the first header file are dealt as header files to be parsed, regardless with their leading "-". For example, "apinames include/freetype/freetype.h -dFREETYPE.DLL" warns "unable to open -dFREETYPE.DLL". Thus, the "header1" must be given after the arguments to be parsed as the options.