Makefile: suppress a sparse warning for pack-revindex.c

Sparse has, for a long time, been issuing the following warning against the pack-revindex.c file: SP pack-revindex.c pack-revindex.c:64:23: warning: memset with byte count of 262144 This results from a unconditional check, with a hard-coded limit, which is really only appropriate for the kernel source code. (The check is for a 'large' byte count in a call to memcpy(), memset(), copy_from_user() and copy_to_user() functions). A recent release of sparse (v0.5.1) has introduced some options to allow this check to be turned off (-Wno-memcpy-max-count) or to specify the actual limit used (-fmemcpy-max-count=COUNT), rather than a hard-coded limit of 100000. In order to suppress the warning, add a target for pack-revindex.sp that adds the '-Wno-memcpy-max-count' option to the SPARSE_FLAGS variable. Signed-off-by: Ramsay Jones <ramsay@ramsayjones.plus.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>