Fix warnings in md5 library.
Uses code from this patch:
http://sourceware.org/git/?p=glibc.git;a=patch;h=7dc6bd90c569c49807462b0740b18e32fab4d8b7
Remove dead code.
Fix various compiler warnings.
Simplify use of signed vs unsigned.
Fixes various compiler warnings. Unsigned chars are now restricted
to the UTF-8 and PatternMatcher functions.