diffcore-rename.c: avoid set-but-not-used warning
diffcore-rename.c: avoid set-but-not-used warning

Since 9d8a5a5 (diffcore-rename: refactor "too many candidates" logic,
2011-01-06), diffcore_rename() initializes num_src but does not use it
anymore.  "-Wunused-but-set-variable" in gcc-4.6 complains about this.

Signed-off-by: Jim Meyering <15b0b14300fba1cff8c70eb2a5c1720ef2a4c654@redhat.com>
Signed-off-by: Junio C Hamano <a6723cc3f76163bf7adb636a73ac3b0ceb3e6b9b@pobox.com>

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