Issue #510 - Stage macos compat fix

Apparently mp_set_double does not compile on OSX. Need to fix up this portion of the code.

runtime.c

@@ -8572,3 +8572,76 @@ void Cyc_get_ratio(void *data, object cont, object n, int numerator)
     return_closcall1(data, cont, &val);
   }
 }
+
+void Cyc_exact(void *data, object cont, object z)
+{
+  int i = 0;
+  Cyc_check_num(data, z);
+  if (obj_is_int(z)) {
+    i = obj_obj2int(z);
+  } else if (type_of(z) == integer_tag) {
+    i = (int)round(((integer_type *)z)->value);
+  } else if (type_of(z) == bignum_tag) {
+    return_closcall1(data, cont, z);
+  } else if (type_of(z) == complex_num_tag) {
+    double dreal = round(creal(((complex_num_type *) z)->value));
+    double dimag = round(cimag(((complex_num_type *) z)->value));
+    make_complex_num(num, dreal, dimag);
+    return_closcall1(data, cont, &num);
+  } else {
+    double d = ((double_type *)z)->value;
+    if (isnan(d)) {
+      Cyc_rt_raise2(data, "Expected number but received", z);
+    } else if (d == INFINITY) {
+      Cyc_rt_raise2(data, "Expected number but received", z);
+    } else if (d == -INFINITY) {
+      Cyc_rt_raise2(data, "Expected number but received", z);
+    } else if (d > CYC_FIXNUM_MAX || d < CYC_FIXNUM_MIN){
+      alloc_bignum(data, bn);
+      BIGNUM_CALL(mp_set_double(&bignum_value(bn), d));
+      return_closcall1(data, cont, bn);
+// TODO: mp_set_double not supported on macos !?!
+#if defined(__STDC_IEC_559__) || defined(__GCC_IEC_559) 
+#endif
+    }
+    i = (int)round(((double_type *)z)->value);
+  }
+  return_closcall1(data, cont, obj_int2obj(i));
+}
+
+object Cyc_exact_no_cps(void *data, object ptr, object z)
+{
+  int i = 0;
+  Cyc_check_num(data, z);
+  if (obj_is_int(z)) {
+    i = obj_obj2int(z);
+  } else if (type_of(z) == integer_tag) {
+    i = (int)round(((integer_type *)z)->value);
+  } else if (type_of(z) == bignum_tag) {
+    return z;
+  } else if (type_of(z) == complex_num_tag) {
+    double dreal = round(creal(((complex_num_type *) z)->value));
+    double dimag = round(cimag(((complex_num_type *) z)->value));
+    double complex unboxed = dreal + (dimag * I);
+    assign_complex_num(ptr, unboxed);
+    return ptr;
+  } else {
+    double d = ((double_type *)z)->value;
+    if (isnan(d)) {
+      Cyc_rt_raise2(data, "Expected number but received", z);
+    } else if (d == INFINITY) {
+      Cyc_rt_raise2(data, "Expected number but received", z);
+    } else if (d == -INFINITY) {
+      Cyc_rt_raise2(data, "Expected number but received", z);
+    } else if (d > CYC_FIXNUM_MAX || d < CYC_FIXNUM_MIN){
+      alloc_bignum(data, bn);
+      BIGNUM_CALL(mp_set_double(&bignum_value(bn), d));
+      return bn;
+// TODO: mp_set_double not supported on macos !?!
+#if defined(__STDC_IEC_559__) || defined(__GCC_IEC_559) 
+#endif
+    }
+    i = (int)round(((double_type *)z)->value);
+  }
+  return obj_int2obj(i);
+}