Like constants, globals on some platforms are GOT relative. This means they have to be allocated

near the GOT, which new doesn't do.  So break out the allocate into a new function.

Also move GOT index handling into JITResolver.  This lets it update the mapping when a Lazy
function is JITed.  It doesn't managed the table, just the mapping.  Note that this is
still non-ideal, as any function that takes a function address should also take a GOT
index, but that is a lot of changes.  The relocation resolve process updates any GOT entry
it sees is out of date.

llvm-svn: 22537