Appreciate your response.
Below is extracted from my config.log(which I suppose is relevant to the problem) -
configure:8971: WARNING: Skipping PostgreSQL plugin (check_pgsql)
configure:8973: WARNING: install lib crypt and PostgreSQL libs to compile this plugin (see REQUIREMENTS).
"/usr/lib/libcrypto*" was shown from running "find".
"libpq-fe.h" is located in "/usr/local/pgsql/include".
I supposed the required libraries and source files are available since the entire Postgresql was built from source. I had done it successfully with other softwares, Asterisk for example, that were dependent on pgsql libs.
I am not running Linux, which is part of the reason pgsql was built from source, and thus cannot install the postgresql-devel package.