review printing ecpg program version

[Ioseph Kim]

hi,

I found a little problem about printing ecpg version.
unlike PostgreSQL ver.11 other programs, ecpg version string has only 
version number.


$ ./ecpg --version
ecpg 11beta3

$ ./psql --version
psql (PostgreSQL) 11beta3

$ ./pg_dump --version
pg_dump (PostgreSQL) 11beta3

I hope PostgreSQL product name be included in ecpg version string,

It will clarify version between other products (ex. EnterpriseDB 
Postgres, GP, ...)


Regards, Ioseph.