[analyzer] Use call graph to determine order in which functions are

analyzed.

The CallGraph is used when inlining is on, which is the current default.

This alone does not bring any performance improvement. It's a
stepping stone for the upcoming optimization in which we do not
re-analyze a function that has already been analyzed while inlined in
other functions. Using the call graph makes it easier to play with
the order of functions to minimize redundant analyzes.

llvm-svn: 152352