[analyzer] Model strsep(), particularly that it returns its input.

This handles the false positive leak warning in PR15374, and also serves
as a basic model for the strsep() function.

git-svn-id: http://llvm.org/svn/llvm-project/cfe/trunk@180069 91177308-0d34-0410-b5e6-96231b3b80d8
When modifying an implicit instantiation with information from an explicit one, make sure to reset the "right brace" location.

Otherwise the source range of the explicit instantiation may become invalid (begin location will be after the end location).

rdar://13706991

git-svn-id: http://llvm.org/svn/llvm-project/cfe/trunk@180070 91177308-0d34-0410-b5e6-96231b3b80d8