Add support for ubsan.

Rather than adding LOCAL_UB_SANITIZER, LOCAL_THREAD_SANITIZER, etc for
each new sanitizer, deprecate LOCAL_ADDRESS_SANITIZER in favor of
LOCAL_SANITZE that mirrors the behavior of -fsanitize=<sanitizers>.

For example, the following will use both asan and ubsan:

    LOCAL_SANITIZE := address undefined

We'll leave LOCAL_ADDRESS_SANITIZER around for compatibility until we
can clean up the tree.

Change-Id: I8a62315129d4753f8e992584ca6db1e5dfdd4d2a
diff --git a/core/clear_vars.mk b/core/clear_vars.mk
index 7837ae3..51cdc5b 100644
--- a/core/clear_vars.mk
+++ b/core/clear_vars.mk
@@ -173,6 +173,7 @@
 LOCAL_NATIVE_COVERAGE :=
 LOCAL_DPI_VARIANTS:=
 LOCAL_DPI_FILE_STEM:=
+LOCAL_SANITIZE:=
 
 # arch specific variables
 LOCAL_SRC_FILES_$(TARGET_ARCH):=