RPM packages for CentOS and derivatives are available via the Fedora "copr" build system; for details see here: https://copr.fedorainfracloud.org/coprs/ibarwick/libfq/
It should be possible to build libfq pn any UNIX-like system. Note that the Firebird header and client library is required, which may be installed as part of the Firebird binary package (e.g. on OS X), or which need to be installed as separate packages (e.g. firebird-devel).
libfq can be installed from source in the usual way:
./configure make make install
The usual configuration options can be specified.
Note that libfq requires Firebird's ibase.h header file, which can be in a non-standard location. Specify its path either with the CFLAGS environment variable or the configure option --with-ibase=DIR.
Typical locations for ibase.h include: