BUG #16543: Package conflicts due to missing llvm-toolset-7-clang >= 4.0.1 and proj70 >= 7.0.1

The following bug has been logged on the website:

Bug reference:      16543
Logged by:          Marco Lechner
Email address:      mlechner@bfs.de
PostgreSQL version: 12.3
Operating system:   RHEL7/OEL7
Description:

As dicussed in pgsql-general on May 28th there are package conflicts when
updating postgresql12 with postgis30:
...
at the moment we are facing similar conflicts on Oracle LInux 7 (wich is
derived from RHEL) – we manage our machines using Spacewalk. The conflicts
occur (as expected) on Spacewalk as well as on manually using yum:

Fehler: Paket: postgresql11-devel-11.8-1PGDG.rhel7.x86_64
(oraclelinux7postgresql11)
            Benötigt: llvm-toolset-7-clang >= 4.0.1
Fehler: Paket: postgis30_12-3.0.1-5.rhel7.x86_64
(oraclelinux7postgresql12)
            Benötigt: proj70 >= 7.0.1
            Installiert: proj70-7.0.0-2.rhel7.x86_64
(@oraclelinux7postgresql11)
                proj70 = 7.0.0-2.rhel7
            Verfügbar: proj70-7.0.0-1.rhel7.x86_64
(oraclelinux7postgresql11)
                proj70 = 7.0.0-1.rhel7
Fehler: Paket: postgresql12-devel-12.3-1PGDG.rhel7.x86_64
(oraclelinux7postgresql12)
            Benötigt: llvm-toolset-7-clang >= 4.0.1
...

These conflicts still seem to exist. @package_maintainer: Please provide the
needed packages.