git-gui: Support of "make -s" in: do not output anything of the build itself
git-gui: Support of "make -s" in: do not output anything of the build itself

Signed-off-by: Alex Riesen <053ce55f4869b7f450d1d77b8f162c6f2bb9e137@gmail.com>
Signed-off-by: Shawn O. Pearce <f01032651c12a22b2103346ba96b3b6b231f9d3c@spearce.org>

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