[analyzer] Tests: move system functions into system header simulator files.

Some checkers ascribe different behavior to functions declared in system
headers, so when working with standard library functions it's probably best
to always have them in a standard location.

Test change only (no functionality change), but necessary for the next commit.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@179552 91177308-0d34-0410-b5e6-96231b3b80d8
3 files changed