Adapt Tokenizer::simplifyCallingConvention() and Tokenizer::simplifyKeyword() for the match compiler

This little change gives another 6% speed improvement on my box.
(tested with the testsuite and checking the 'rpm' codebase)

The profiler showed we were spending quite some time in
Tokenizer::simplifyCallingConvention(). The multi match
pattern in there is "complex", at least for the on-the-fly parser.