Cannot set MellonDiagnosticsEnable=on because mod_auth_mellon isn't compiled with --enable-diagnostics

Issue

• Cannot set MellonDiagnosticsEnable as we get the following error messages:

[heat-admin@overcloud-controller-0 ~]$ sudo service httpd configtest
[Mon Jun 10 11:03:32.687536 2019] [auth_mellon:notice] [pid 151427] MellonDiagnosticsFile has no effect because Mellon was not compiled with diagnostics enabled, use ./configure --enable-diagnostics at build time to turn this feature on.
[Mon Jun 10 11:03:32.687722 2019] [auth_mellon:notice] [pid 151427] MellonDiagnosticsEnable has no effect because Mellon was not compiled with diagnostics enabled, use ./configure --enable-diagnostics at build time to turn this feature on.