Fixed an issue I found in the mach-o symbol table parsing where

we cached remapping information using the old nlist index to the
new symbol index, yet we tried to lookup the symbol stubs that
were for symbols that had been remapped by ID instead of using
the new symbol index. This is now fixed and the mach-o symbol tables
are fixed.

Use the delta between two vector entries to determine the stride
in case any padding is inserted by compilers for bsearch calls
on symbol tables when finding symbols by their original ID.

llvm-svn: 113719