The sign information was not propagating into the rename map so only the

last entry stored in the map could be retrieved for a given integer type.
Propagating the sign information required an invasive change to ensure that
all ValueRef (ValID) instances get the right sign information as well. Also,
put in some assertions to ensure the RenameMap always gives us out the type
that is expected.

This fixes PR1256 and
test/Assembler/2007-03-14-UgpradeLocalSignless.ll

llvm-svn: 35112