Remove explicit FORTIFY_SOURCE flag

Local installation of the library complains of redefinition of this
flag, so remove the explicit definition. The default should be 3.

BUG=b:296063204
TEST=check that:
```
cd ~/trumk/src/platform/touchpad-tests
sudo make setup-in-place
touchtests
```
passes.

Change-Id: I9b94a90858d2be04a819ddcedd2143b819bb1fdb
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/libevdev/+/4957255
Reviewed-by: Denis Brockus <dbrockus@chromium.org>
Commit-Queue: Sean O'Brien <seobrien@chromium.org>
Tested-by: Sean O'Brien <seobrien@chromium.org>
1 file changed