Rename AnalysisContext to AnalysisDeclContext.  Not only is this name more accurate, but it frees up the name AnalysisContext for other uses.

llvm-svn: 142782

 - Remodel Expr::EvaluateAsInt to behave like the other EvaluateAs* functions,
   and add Expr::EvaluateKnownConstInt to capture the current fold-or-assert
   behaviour.
 - Factor out evaluation of bitfield bit widths.
 - Fix a few places which would evaluate an expression twice: once to determine
   whether it is a constant expression, then again to get the value.

llvm-svn: 141561

llvm-svn: 140648

[analyzer] Refactor PathDiagnosticLocation: Make PathDiagnosticLocation(SourceLocation...) private. Most of the effort here goes to making BugReport refer to a PathDiagnosticLocation instead of FullSourceLocation. 

(Another step closer to the goal of having Diagnostics which can recover from invalid SourceLocations.)

llvm-svn: 140182

[analyzer] Introduce MallocOverflowSecurityChecker, a simple flow-sensitive checker that may be useful for security auditing.  This checker is currently too noisy to be on by default.

llvm-svn: 136804