[PATCH] apidoc mismatch for Perl_magic_clearhint

Perl_magic_clearhint has its apidoc corresponding titled magic_sethint, 
most likely some remains of a wild cut/paste. Fixed with the patch attached.

• [PATCH] apidoc mismatch for Perl_magic_clearhint by Vincent Pit
• Re: [PATCH] apidoc mismatch for Perl_magic_clearhint by Rafael Garcia-Suarez