discard_cache(): discard index, even if no file was mmap()ed
discard_cache(): discard index, even if no file was mmap()ed

Since add_cacheinfo() can be called without a mapped index file,
discard_cache() _has_ to discard the entries, even when
cache_mmap == NULL.

Signed-off-by: Johannes Schindelin <53fb8db7833fca1e1746dd8592f61048d350f64c@gmx.de>
Signed-off-by: Junio C Hamano <dc50d1021234060e53ec42a77d526afa2fe07479@cox.net>

destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git