fix RST reference in Writing an LLVM Pass

Currently, instead of showing up as link, it is rendered as

  ...of FunctionPass <writing-an-llvm-pass-FunctionPass>. The...

PR17733. Patch by Tay Ray Chuan!

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@193698 91177308-0d34-0410-b5e6-96231b3b80d8
DwarfDebug: Change Abbreviations member from pointer to reference

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@193699 91177308-0d34-0410-b5e6-96231b3b80d8
R600: Custom lower f32 = uint_to_fp i64

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@193701 91177308-0d34-0410-b5e6-96231b3b80d8