Fix mkpath abuse in dwim_ref and dwim_log of sha1_name.c
Fix mkpath abuse in dwim_ref and dwim_log of sha1_name.c

Otherwise the function sometimes fail to resolve obviously correct
refnames, because the string data pointed to by "str" argument were
reused.

The change in dwim_log does not fix anything, just optimizes away
strcpy code as the path can be created directly in the available
buffer.

Signed-off-by: Alex Riesen <053ce55f4869b7f450d1d77b8f162c6f2bb9e137@gmail.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