cmath: Fix compilation error on macOS with sincos

dtool/src/dtoolbase/cmath.I

@@ -64,6 +64,8 @@ csincos(float v, float *sin_result, float *cos_result) {
       fstp DWORD ptr [edx]
       fstp DWORD ptr [eax]
       }
+#elif defined(__APPLE__)
+  __sincosf(v, sin_result, cos_result);
 #elif defined(_GNU_SOURCE)
   sincosf(v, sin_result, cos_result);
 #else
@@ -233,6 +235,8 @@ csincos(double v, double *sin_result, double *cos_result) {
       fstp QWORD ptr [edx]
       fstp QWORD ptr [eax]
       }
+#elif defined(__APPLE__)
+  __sincos(v, sin_result, cos_result);
 #elif defined(_GNU_SOURCE)
   sincos(v, sin_result, cos_result);
 #else //!_X86_