Cleanup of compilation flags for gcc and clang

o no-schedule-insns, no-inline  is not needed at O0
Use -Wno-deprecated-declarations also for clang builds
Speedup root startup by 10%
Revert "Speedup root startup by 10%"

Check the evolution of the suspicious failures in cdash.

This reverts commit fc133d400878f20b2c182e6a37ca01e87e46f390.
Do not add twice enums in namespaces when they come from rootpcms
Get right the re-loading of enums coming from protoclasses.

We need to remove the re-loaded enums from the unloaded list
if the enums come from protoclasses. This is necessary to avoid the
presence of duplicates in the typesystem.