autoconf compiling *.c

Hi Adam,

for support of keyword checking, we need to include keywords.c. I added
this to makefile.am, but the compile flags will lacke the including of
the main include dir (../src/include in my build). While we have agreed
not to activate this for the 1.0 release, we'll need this quite soon.
Please have a look where to add the options so we can compile *.c
successfully.

Regards,
Andreas