Include Address Sanitizer when sanitizers are enabled

In practice, this is just when running unit tests.

BUG=b:318520168
TEST=add -fsanitize=address to compiler flags, run unit tests [0], and
     check no address sanitization failures are reported

[0]: cros_sdk env FEATURES="test" emerge-${BOARD} chromeos-base/gestures

Change-Id: Ifd8c335413238a1c0477100532a575d049a76261
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/gestures/+/5318358
Tested-by: Harry Cutts <hcutts@chromium.org>
Reviewed-by: Sean O'Brien <seobrien@chromium.org>
Commit-Queue: Harry Cutts <hcutts@chromium.org>
Code-Coverage: Sean O'Brien <seobrien@chromium.org>
diff --git a/Makefile b/Makefile
index 4d09402..9adcf1e 100644
--- a/Makefile
+++ b/Makefile
@@ -131,10 +131,10 @@
 
 ifeq (yes,$(SANITIZE_GESTURES))
 CXXFLAGS+=\
-	-fsanitize=undefined \
+	-fsanitize=address,undefined \
 	-fno-sanitize-recover=all
 LINK_FLAGS+=\
-	-fsanitize=undefined \
+	-fsanitize=address,undefined \
 	-fno-sanitize-recover=all
 endif