Merge diagnostic group tables to reduce data size and relocation entries.

The individual group and subgroups tables are now two large tables. The option table stores an index into these two tables instead of pointers. This reduces the size of the options tabe since it doesn't need to store pointers. It also reduces the number of relocations needed.

My build shows this reducing DiagnosticsIDs.o and the clang binary by ~20.5K. It also removes ~400 relocation entries from DiagnosticIDs.o.






git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@189438 91177308-0d34-0410-b5e6-96231b3b80d8
Disable loop vectorizer unrolling when no unrolling requested

In addition to the regular loop unrolling transformation, the loop vectorizer
can also unroll loops. If no unrolling has specifically been requested (by
-fno-unroll-loops), and the loop vectorizer will be used, then add the backend
option to (also) prevent the loop vectorizer from unrolling loops.

I confirmed with Nadav (off list) that disabling vectorizer loop unrolling when
-fno-unroll-loops is provided is the desired behavior.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@189440 91177308-0d34-0410-b5e6-96231b3b80d8