Sanitizer build tweaks.

-Wl,-no-undefined is currently disabled for any SANITIZE_TARGET. Limit that to
the sanitizers with a runtime library (i.e. address, thread).

Re-enable the relocation packer for ASan. This has been fixed upstream a long
time ago.

Bug: 27729263
Change-Id: I566df6104de816223dc1c519d41a87629ce9c47c
diff --git a/core/config_sanitizers.mk b/core/config_sanitizers.mk
index 6b18be5..b69a6ce 100644
--- a/core/config_sanitizers.mk
+++ b/core/config_sanitizers.mk
@@ -55,17 +55,13 @@
 # sanitized static libraries. That's OK, because the executable
 # always depends on the ASan runtime library, which defines these
 # symbols.
-ifneq ($(strip $(SANITIZE_TARGET)),)
+ifneq ($(filter address thread,$(strip $(SANITIZE_TARGET))),)
   ifndef LOCAL_IS_HOST_MODULE
     ifeq ($(LOCAL_MODULE_CLASS),SHARED_LIBRARIES)
       ifeq ($(my_sanitize),)
         my_allow_undefined_symbols := true
       endif
     endif
-    # Workaround for a bug in AddressSanitizer that breaks stack unwinding.
-    # https://code.google.com/p/address-sanitizer/issues/detail?id=387
-    # Revert when external/compiler-rt is updated past r236014.
-    LOCAL_PACK_MODULE_RELOCATIONS := false
   endif
 endif