naemon/Makefile.am: Add wpres-phash.h to CLEANFILES

Signed-off-by: Adam James <adam.james@transitiv.co.uk>
autotools: Detect supported compiler flags

This commit adds an autoconf macro that checks for supported compiler
flags. We use this to dynamically build AM_CFLAGS in configure.ac.

Preprocessor defines have been moved into AM_CPPFLAGS and CFLAGS to
AM_CFLAGS. This allows users to negate certain flags should they so
wish.

Signed-off-by: Adam James <adam.james@transitiv.co.uk>
Merge pull request #8 from atj/autotools

Autotools updates