Makefile: export NO_SVN_TESTS

Without this patch, it really is not sufficient to define NO_SVN_TESTS
in config.mak or the Makefile.

Signed-off-by: Johannes Schindelin <Johannes.Schindelin@gmx.de>
Signed-off-by: Junio C Hamano <junkio@cox.net>

Makefile

@@ -656,6 +656,7 @@ GIT-CFLAGS: .FORCE-GIT-CFLAGS
 # with that.
 
 export NO_PYTHON
+export NO_SVN_TESTS
 
 test: all
 	$(MAKE) -C t/ all