Add new warning -Wrange-loop-analysis to warn on copies during loops.
-Wrange-loop-analysis is a subgroup of -Wloop-analysis and will warn when
a range-based for-loop makes copies of the elements in the range. If possible,
suggest the proper type to prevent copies, or the non-reference to help
distinguish copy versus non-copy forms. Existing warnings in -Wloop-analysis
are moved to -Wfor-loop-analysis, also a subgroup of -Wloop-analysis.
Differential Revision: http://reviews.llvm.org/D4169