ART: remove ART_JIT makefile variable

The ART_JIT variable isn't used (and was never used?).

Test: mma, make test-art-host, make test-art-target
Change-Id: Ie6463c3c13fab43504f3c60fd5a15f696e2cf481
diff --git a/build/Android.common_build.mk b/build/Android.common_build.mk
index a679ac2..e89a381 100644
--- a/build/Android.common_build.mk
+++ b/build/Android.common_build.mk
@@ -76,18 +76,6 @@
 endif
 
 #
-# Used to enable JIT
-#
-ART_JIT := false
-ifneq ($(wildcard art/JIT_ART),)
-$(info Enabling ART_JIT because of existence of art/JIT_ART)
-ART_JIT := true
-endif
-ifeq ($(WITH_ART_JIT), true)
-ART_JIT := true
-endif
-
-#
 # Used to change the default GC. Valid values are CMS, SS, GSS. The default is CMS.
 #
 ART_DEFAULT_GC_TYPE ?= CMS