Paul,

Thanks very match.  I checked the patch, and I add fixes to it as
following.

 1. Fixed warning.

    dfa.c: In function 'build_mbrtowc_cache':
    dfa.c:448: warning: pointer targets in passing argument 1 of
    'mbrtowc' differ in signedness

 2. took mbrtowc_cache into new member of struct dfa.

    When struct dfa more than one are used at the same time, mbrtowc cache
    may be conflict.  So, take mbrtowc_cache into new member of struct dfa,
    and define each mbrtowc cache for them.

Norihiro