Fixed "note:" output when compiling filemagic.c

[joast]

Increased version string temporary buffers from 8 to 16 bytes to suppress the following note, and 17 or 18 other lines of output, when compiling filemagic.c:

note: ‘sprintf’ output between 5 and 14 bytes into a destination of size 8

Update: I was using a few different versions of gcc. Tested with a few versions of clang and got similar warnings.