compiling postgresql with uuid-ossp failure

I have installed idempiere ERP which requires uuid-ossp library. I have tried to recompile postgresql-11.2 with the option --with-uuid=ossp. When run I

CREATE EXTENSION "uuid-ossp";

I get the following error:

ERROR:  could not open extension control file "/data/databases/postgres/pgsql11/share/extension/uuid-ossp.control": No such file or directory.

 select * from pg_available_extensions;

gives me this list  (without uuid-ossp, of course):

 name    | default_version | installed_version |                  comment                 
------------+-----------------+-------------------+-------------------------------------------
 pltclu     | 1.0             |                   | PL/TclU untrusted procedural language
 pltcl      | 1.0             |                   | PL/Tcl procedural language
 plperl     | 1.0             |                   | PL/Perl procedural language
 plperlu    | 1.0             |                   | PL/PerlU untrusted procedural language
 plpythonu  | 1.0             |                   | PL/PythonU untrusted procedural language
 plpython2u | 1.0             |                   | PL/Python2U untrusted procedural language
 plpgsql    | 1.0             | 1.0               | PL/pgSQL procedural language
(7 rows)

 Is there a reason why this extension was not created during compilation/installation?

Thanks