Externals reorganization 2011

Eliminating the "Compiler" path element

Including a subdirectory named after compiler in the path for each external has been a mixed blessing at best. In particular it causes problems for those wishing to build a check-out package with a compiler version not among those used by the Release Manager. We propose to eliminate the compiler element in new RM builds only, to minimize disruption. Steps towards this aim are described below.

Create new externals

For each external in active use (CVS head only or also for GR Pass7 branch?) and for each supported operating system, for each version of that external in current use,  create a new external version  by copying the original external to the new structure.  The new external name will have a suffix -glN, where N is the next available number, to distinguish it from the old.