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

Signed-off-by: Alex Riesen <raa.lkml@gmail.com>
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>

Makefile

@@ -27,6 +27,11 @@ ifndef V
 	QUIET_BUILT_IN = @echo '   ' BUILTIN $@;
 endif
 
+ifeq ($(findstring $(MAKEFLAGS),s),s)
+QUIET_GEN =
+QUIET_BUILT_IN =
+endif
+
 DESTDIR_SQ = $(subst ','\'',$(DESTDIR))
 gitexecdir_SQ = $(subst ','\'',$(gitexecdir))
 SHELL_PATH_SQ = $(subst ','\'',$(SHELL_PATH))