pgsql: ecpg requires libpq; add Makefile rules to require libpq to be

Log Message:
-----------
ecpg requires libpq; add Makefile rules to require libpq to be built
first.

Alvaro Herrera

Modified Files:
--------------
pgsql/src/interfaces/ecpg/ecpglib:
Makefile (r1.62 -> r1.63)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/interfaces/ecpg/ecpglib/Makefile?r1=1.62&r2=1.63)