8250688: missed open parenthesis for GTEST_FRAMEWORK_SRC var in Main.gmk

Reviewed-by: erikj
diff --git a/make/Main.gmk b/make/Main.gmk
index 3e5450c..0b02f74 100644
--- a/make/Main.gmk
+++ b/make/Main.gmk
@@ -664,7 +664,7 @@
     DEPS := build-test-hotspot-jtreg-graal, \
 ))
 
-ifneq ($GTEST_FRAMEWORK_SRC), )
+ifneq ($(GTEST_FRAMEWORK_SRC), )
   $(eval $(call SetupTarget, test-image-hotspot-gtest, \
       MAKEFILE := hotspot/test/GtestImage, \
       DEPS := hotspot, \