signal handler works partially. tested with signal.ml in testsuite. Signal sent to the process will be delievered to a random thread. The signal funs will call handler function with the context pointer given by Sys.signal-caller thread. The pointer is stored in a global var handler_ctx
testsuite arrays.ml runs without error. cmmgen.ml:Cextcall, stdlib_r/pervasives
testing in progress.. basic-float
cross-phc works well
no scan tag shifting seems to work. test on nqueen_r passed