$ apr-config --cflags
==> -g -Wmissing-prototypes -Wstrict-prototypes -Wmissing-declarations -pthread
BUT:
$ apxs2 -q CFLAGS
==> -O2 -march=i586 -mcpu=i686 -fmessage-length=0 -fPIC -Wall -fno-strict-aliasing -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64