fix "make upgrade" broken in r2759

auto/install

diff --git a/auto/install b/auto/install
index 91f9710..c17dac6 100644
--- a/auto/install
+++ b/auto/install
@@ -124,3 +124,39 @@
 END
 
 fi
+
+
+# create Makefile
+
+cat << END >> Makefile
+
+build:
+	\$(MAKE) -f $NGX_MAKEFILE
+
+install:
+	\$(MAKE) -f $NGX_MAKEFILE install
+
+upgrade:
+	$NGX_SBIN_PATH -t
+
+	kill -USR2 \`cat $NGX_PID_PATH\`
+	sleep 1
+	test -f $NGX_PID_PATH.oldbin
+
+	kill -QUIT \`cat $NGX_PID_PATH.oldbin\`
+
+upgrade1:
+	# upgrade 0.1.x to 0.2+
+
+	$NGX_SBIN_PATH -t
+
+	cp $NGX_PID_PATH $NGX_PID_PATH.oldbin
+
+	kill -USR2 \`cat $NGX_PID_PATH\`
+	sleep 1
+	test -f $NGX_PID_PATH.oldbin
+
+	cp $NGX_PID_PATH $NGX_PID_PATH.newbin
+
+	kill -QUIT \`cat $NGX_PID_PATH.oldbin\`
+END