Add -Wfor-loop-analysis to -Wall.

This warning seems to have 0 false positives and some true positives in
practice, without a measurable compile time cost.  It should be in -Wall, and
possibly even become a default warning at some point.

llvm-svn: 256975

clang/include/clang/Basic/DiagnosticGroups.td

@@ -616,6 +616,7 @@ def Most : DiagGroup<"most", [
     CharSubscript,
     Comment,
     DeleteNonVirtualDtor,
+    ForLoopAnalysis,
     Format,
     Implicit,
     InfiniteRecursion,