In Debian it is good to propagate CFLAGS (and other compiler flags into
upstream Makefile. I fixed the patch to accomplish this and have
standard build flags (which are generated from the hardening option
for instance) as well as the recommended flags.
The resulting package does not yet feature any build results which is as
far as I see a development library. That means the package name should
be probably
libampl-netlib-solvers-dev
Please make sure the *.a file that is build will be installed. I'd
recomment to have a look for instance into
https://salsa.debian.org/med-team/libvcflib/-/blob/master/debian/libvcflib-dev.install
(well, there is a *.so file installed but the point is that it is installed
in DEB_HOST_MULTIARCH). You also need to add dh-exec to Build-Depends.
Usually also *.h files need to be installed.