git-gui: Handle ' within paths when creating Windows shortcuts.

Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
diff --git a/git-gui b/git-gui
index c35c73c..013f21b 100755
--- a/git-gui
+++ b/git-gui
@@ -2049,6 +2049,8 @@
 					--unix \
 					--absolute \
 					$gitdir]
+				regsub -all ' $me "'\\''" me
+				regsub -all ' $gd "'\\''" gd
 				puts -nonewline $fd "\"$sh\" --login -c \""
 				puts -nonewline $fd "GIT_DIR='$gd'"
 				puts -nonewline $fd " '$me'"