[RuntimeDyld] Add casts to make delta computation 64-bit.

Hopefully this will fix the i686/msvc build failure described at:
http://bb.pgr.jp/builders/ninja-clang-i686-msc18-R/builds/803



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@234977 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed