Expand auto for readability.

git-svn-id: https://llvm.org/svn/llvm-project/lld/trunk@192162 91177308-0d34-0410-b5e6-96231b3b80d8
Make bitmask an unsigned type.

git-svn-id: https://llvm.org/svn/llvm-project/lld/trunk@192163 91177308-0d34-0410-b5e6-96231b3b80d8
Remove an unnecessary local variable.

git-svn-id: https://llvm.org/svn/llvm-project/lld/trunk@192164 91177308-0d34-0410-b5e6-96231b3b80d8
Use size_t instead of uint64_t to represent the vector length.

git-svn-id: https://llvm.org/svn/llvm-project/lld/trunk@192165 91177308-0d34-0410-b5e6-96231b3b80d8