[sanitizer] On OS X, verify that interceptors work and abort if not

[sanitizer] On OS X, verify that interceptors work and abort if not

On OS X 10.11+, we have "automatic interceptors", so we don't need to use DYLD_INSERT_LIBRARIES when launching instrumented programs. However, non-instrumented programs that load TSan late (e.g. via dlopen) are currently broken, as TSan will still try to initialize, but the program will crash/hang at random places (because the interceptors don't work). This patch adds an explicit check that interceptors are working, and if not, it aborts and prints out an error message suggesting to explicitly use DYLD_INSERT_LIBRARIES.

Differential Revision: http://reviews.llvm.org/D18121

llvm-svn: 263551