[analyzer] [NFC] remove duplicated function
[analyzer] [NFC] remove duplicated function

Two copies of getSymLERange in RangeConstraintManager are virtually
identical, which is clearly bad.
This patch uses lambdas to call one from another (assuming that we would
like to avoid getting ranges from the state when necessary).

Differential Revision: https://reviews.llvm.org/D39709

git-svn-id: ffe668792ed300d6c2daa1f6eba2e0aa28d7ec6c@319697 91177308-0d34-0410-b5e6-96231b3b80d8
(cherry picked from commit b873ee35bb7121eadda09a249db2b20c58b8ab1f)

apple/swift-clang,apple/swift-clang,apple/swift-clang,apple/swift-clang,apple/swift-clang,apple/swift-clang,apple/swift-clang,apple/swift-clang,apple/swift-clang,apple/swift-clang