Fixes the test on OS X
-fvia-c is now a no-op
The underlying problem in ticket #5003 is not in ghc, but rather that the test condition runs off the end of the C stack on 64 bit processors. Test 4038 does a recursive call of a simple external function. Each invocation of the function allocates a bit over 16 kB of C stack on a 64 bit processor (half as much on a 32 bit processor). The typical C stack on a unix system is 8 MB, so after no more than about 500 nested calls the stack pointer will move past the end of the allocated stack and cause a segfault. The fix is to not call the function as many times. I've made the number of calls a constant and have added a note explaining its value. With this patch test 4038 passes consistently on OS X 64 bit.