Remove references to MALLOC_LEAK_CHECK.

This define isn't really used any more.

Bug: 17378595
Change-Id: I39722b83cd98955a3a2514577de34a239524617f
diff --git a/libc/Android.mk b/libc/Android.mk
index 0f828ed..1164301 100644
--- a/libc/Android.mk
+++ b/libc/Android.mk
@@ -1120,10 +1120,7 @@
 # ========================================================
 include $(CLEAR_VARS)
 
-LOCAL_CFLAGS := \
-    $(libc_common_cflags) \
-    -DMALLOC_LEAK_CHECK \
-
+LOCAL_CFLAGS := $(libc_common_cflags)
 LOCAL_CONLYFLAGS := $(libc_common_conlyflags)
 LOCAL_CPPFLAGS := $(libc_common_cppflags)