Sometimes it can be useful to build things without the autoconf ./configure machinery, and just use a simple and hand-maintained makefile and config.h. This is needed to build things in older uClinux environments. I wrote some instructions on how to build GnuTLS and GNU SASL, and their dependencies (libgpg-error, libgcrypt, libtasn1) without running ./configure, see:
http://josefsson.org/uclinux/old/
The makefile/config.h aren’t specific to uClinux, so if you for some reason need to build these projects in some other environment, without autoconf, the files may be useful.
(Although if you want to build GnuTLS/GSASL properly under a modern uClinux, you’ll be better of reading an earlier post.)