Prevent infinite loop when trimming the path cache

Change-Id: I04b5fa498336068f997c68d8613b35a99f67adbe
diff --git a/libs/hwui/ShapeCache.h b/libs/hwui/ShapeCache.h
index 58fea08..92314b0 100644
--- a/libs/hwui/ShapeCache.h
+++ b/libs/hwui/ShapeCache.h
@@ -717,7 +717,9 @@
             ALOGD("Shape %s deleted, size = %d", mName, size);
         }
 
-        glDeleteTextures(1, &texture->id);
+        if (texture->id) {
+            glDeleteTextures(1, &texture->id);
+        }
         delete texture;
     }
 }