Set GEM to gem1.9.1 only if it doesn't already have a value

Michael Klishin · Michael Klishin · commit a11085b8b568 · 2013-07-25T10:58:47.000+04:00
diff --git a/Makefile b/Makefile
@@ -108,7 +108,8 @@ clean::
 	(cd php && \
 		rm -rf .ok lib)
 
-GEM=gem1.9.1
+GEM=$(GEM)
+GEM?=gem1.9.1
 TOPDIR:=$(PWD)
 ruby/.ok:
 	(cd ruby && \
