Apply fixes for cppcheck nitpicks.

  http://cppcheck.sourceforge.net/

Note that the current version heavily chokes on FreeType, delivering
even wrong results.  I will report those issues to the cppcheck team
so that a newer version gives improved results hopefully.

*/* Improve variable scopes.
*/* Remove redundant initializations which get overwritten.

* src/base/ftmac.c ,builds/mac/ftmac.c (count_faces_scalable):
Remove unused variable.

* src/base/ftdbgmem.c (ft_mem_table_destroy): `table' can't be zero.

* src/gxvalid/gxvkern.c (gxv_kern_subtable_fmt1_entry_validate):
Remove functionless code.

* src/tools/ftrandom.c (main): Fix memory leak.