Using VMCWORKDIR in gconfig directory

While most of the occurrences of VMCWORKDIR variable in our code have been replaced by (recommended) MPDROOT we still need to change it in files gconfig/g4Config.C, rootlogon.C, and viewrootgeo.c. When doing so, it is a good time to add compilation tests to these macros.

To upload designs, you'll need to enable LFS and have an admin enable hashed storage. More information