[analyzer] Use BFS over call graph when analysing functions.
[analyzer] Use BFS over call graph when analysing functions.

BFS should give slightly better performance. Ex: Suppose, we have two
roots R1 and R2. A callee function C is reachable through both. However,
C is not inlined when analyzing R1 due to inline stack depth limit. With
DFS, C will be analyzed as top level even though it would be analyzed as
inlined through R2. On the other hand, BFS could avoid analyzing C as
top level.

git-svn-id: ffe668792ed300d6c2daa1f6eba2e0aa28d7ec6c@152652 91177308-0d34-0410-b5e6-96231b3b80d8

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