Similar to what was already done for static initializers, we need to
unlock the state mutext when calling out to libobjc to run +load methods
in case they cause us to reenter the runtime, which was previously
deadlocking. No test for now, because we don't have any code paths in
llvm-jitlink itself that could lead to this deadlock. If we interpose
calls to dlopen to go back to the JIT in the future then calling dlopen
from a +load is the easiest way to reproduce this.
rdar://133430490
fa089efa6c