This patch fixes a bug with the updating of DBG_VALUE's in
BreakAntiDependencies. Previously, it would only attempt to update the first
DBG_VALUE following the instruction whose register is being changed,
potentially leaving DBG_VALUE's referring to the wrong register. Now the code
will attempt to update all DBG_VALUE's that immediately follow the instruction.
This issue was detected as a result of an optimized codegen difference with
"-g" where an X86 byte/word fixup was not performed due to a DBG_VALUE
referencing the wrong register.