msvc: update Makefile to allow for spaces in the compiler path

It is quite common that MS Visual C++ is installed into a location whose
path contains spaces, therefore we need to quote it.

Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Makefile

@@ -1235,7 +1235,7 @@ endif
 
 ifdef SANE_TOOL_PATH
 SANE_TOOL_PATH_SQ = $(subst ','\'',$(SANE_TOOL_PATH))
-BROKEN_PATH_FIX = 's|^\# @@BROKEN_PATH_FIX@@$$|git_broken_path_fix $(SANE_TOOL_PATH_SQ)|'
+BROKEN_PATH_FIX = 's|^\# @@BROKEN_PATH_FIX@@$$|git_broken_path_fix "$(SANE_TOOL_PATH_SQ)"|'
 PATH := $(SANE_TOOL_PATH):${PATH}
 else
 BROKEN_PATH_FIX = '/^\# @@BROKEN_PATH_FIX@@$$/d'