libevdev: update to _FORTIFY_SOURCE=3

Since this project explicitly specifies its FORTIFY level, update it to
the level CrOS wants to move to. This isn't _removed_, since it's copied
from a template file, and consistency with that seems useful.

BUG=b:288411201
TEST=CQ+1

Change-Id: I310bc3d0871ab4c2c157be94544f3dd949e1c8a0
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/libevdev/+/4708107
Tested-by: George Burgess <gbiv@chromium.org>
Reviewed-by: Sean O'Brien <seobrien@chromium.org>
Commit-Queue: George Burgess <gbiv@chromium.org>
diff --git a/common.mk b/common.mk
index 7939883..a3b3e98 100644
--- a/common.mk
+++ b/common.mk
@@ -282,7 +282,7 @@
 COMMON_CFLAGS := -Wall -Werror -fno-strict-aliasing -O1 -Wformat=2
 CXXFLAGS += $(COMMON_CFLAGS) $(COMMON_CFLAGS-$(CXXDRIVER))
 CFLAGS += $(COMMON_CFLAGS) $(COMMON_CFLAGS-$(CDRIVER))
-CPPFLAGS += -D_FORTIFY_SOURCE=2
+CPPFLAGS += -D_FORTIFY_SOURCE=3
 
 
 ifeq ($(MODE),opt)