#8 configure.in - using more variables from apxs

I couldn't compile mod_cplusplus with apr compiled with
large file support because it couldn't have found
off64_t. _LARGEFILE64_SOURCE should be defined during
compilation, but apxs prints it in EXTRA_CPPFLAGS with
is not used by default. This patch makes configure to
get more variables from apxs which will be used during
compilation.

Better fix would be to use apxs -c option, but it's up
to you to decide.

[Anonymous]