build: rename LOCAL_32BIT_ONLY to LOCAL_32_BIT_ONLY

Rename for consistency with TARGET_IS_64_BIT.

Change-Id: I824dcaed0c1e88b8246bcffb21ab3f1772175926
diff --git a/core/prebuilt.mk b/core/prebuilt.mk
index d5fa4ba..de0d92c 100644
--- a/core/prebuilt.mk
+++ b/core/prebuilt.mk
@@ -16,7 +16,7 @@
 $(error dont use LOCAL_PREBUILT_JAVA_LIBRARIES anymore LOCAL_PATH=$(LOCAL_PATH))
 endif
 
-ifneq ($(TARGET_IS_64_BIT)|$(LOCAL_32BIT_ONLY),true|true)
+ifneq ($(TARGET_IS_64_BIT)|$(LOCAL_32_BIT_ONLY),true|true)
 # Build for TARGET_ARCH
 LOCAL_2ND_ARCH_VAR_PREFIX :=
 else