[ASan] Make sure operator new/delete and friends are intercepted on OS X.
Because the interceptors will reside in a dylib, not the main executable, we can't just declare them,
but must use the interposition machinery.
Fix the test expectations in large_func_test.cc affected by the change.
This CL should make our Mac buildbots green.


git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@175763 91177308-0d34-0410-b5e6-96231b3b80d8