Edit the conf-compile/conf-cc and conf-compile/conf-ld files.
The first line of these files should contain the command which will be used
to compile (respectively link) the software.
For instance, if you're a Linux user and want to compile skarnet.org
software with the dietlibc
instead of the GNU libc,
you can perform
echo diet -Os gcc > conf-compile/conf-cc echo diet -Os gcc -s > conf-compile/conf-ld
before compiling the package. I recommend this to any Linux user.
There is a bug in the strip binary, in OpenBSD up to 3.2, which prevents the skarnet.org packages from building out-of-the-box. The bug has been corrected in OpenBSD-3.3. If you can't upgrade, you can prevent the libraries from being stripped:
echo > conf-compile/conf-striplibs
The build should then work flawlessly.
I have a separate page explaining the details of the build process.