- boo#1216734: Revert the last change and make the devel package
independend of all other subpackages except for the libs.

- boo#1216022: Call install-alternatives from the devel subpackage
as well, otherwise the symlink for ecpg might be missing.

- Also buildignore the postgresql*-implementation symbols: this is
needed in order to bootstrap when no postgresql version currently
has valid symbols provided. Once the packages are built, OBS
could translate this to the pgname-* packages and accept the
ignores; during bootstrap though, there is nothing providing the
symbol and the existing buildignores do not suffice.