Fix installation

The build system thought that the RTS built more library files than
it actually did, and installation failed when we tried to 'strip'
one of these non-existant files.
In build.mk.sample, include v in GhcLibWays even if DYNAMIC_GHC_PROGRAMS is set

Although it's not technically needed, it's less confusing if the vanilla
way works when people use the sample build.mk.