package/apr: fix non-portable atomics

package/apr: fix non-portable atomics

apr-1.7.0 added support for 8 bytes atomics for 32 bit archs
https://github.com/apache/apr/commit/2f61f960c81e4a45f3849baa7563812e7e526436

We need to adjust our _CONF_OPTS which fixes an apache build error.

Fixes:
http://autobuild.buildroot.net/results/f24/f2461c1ed542e050afd761db5faeaaff1f51775b/

Signed-off-by: Bernd Kuhls <bernd.kuhls@t-online.de>
Reviewed-by: Giulio Benetti <giulio.benetti@micronovasrl.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>