Add support for building the compactiontable for bytecode files. This shrinks

Add support for building the compactiontable for bytecode files.  This shrinks
the bytecode file for 176.gcc by about 200K (10%), and 254.gap by about 167K,
a 25% reduction.  There is still a lot of room for improvement in the encoding
of the compaction table.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@10913 91177308-0d34-0410-b5e6-96231b3b80d8