py/modmath: Make log2, log10 and hyperbolic funcs be SPECIAL_FUNCTIONS.

Will be included only when MICROPY_PY_MATH_SPECIAL_FUNCTIONS is enabled.

Also covers cmath module (but only log10 is there at the moment).
diff --git a/py/modmath.c b/py/modmath.c
index 423ad4c..b7aa592 100644
--- a/py/modmath.c
+++ b/py/modmath.c
@@ -68,7 +68,6 @@
 #if MICROPY_PY_MATH_SPECIAL_FUNCTIONS
 /// \function expm1(x)
 MATH_FUN_1(expm1, expm1)
-#endif
 /// \function log2(x)
 MATH_FUN_1(log2, log2)
 /// \function log10(x)
@@ -85,6 +84,7 @@
 MATH_FUN_1(asinh, asinh)
 /// \function atanh(x)
 MATH_FUN_1(atanh, atanh)
+#endif
 /// \function cos(x)
 MATH_FUN_1(cos, cos)
 /// \function sin(x)
@@ -198,6 +198,7 @@
     { MP_OBJ_NEW_QSTR(MP_QSTR_expm1), (mp_obj_t)&mp_math_expm1_obj },
     #endif
     { MP_OBJ_NEW_QSTR(MP_QSTR_log), (mp_obj_t)&mp_math_log_obj },
+    #if MICROPY_PY_MATH_SPECIAL_FUNCTIONS
     { MP_OBJ_NEW_QSTR(MP_QSTR_log2), (mp_obj_t)&mp_math_log2_obj },
     { MP_OBJ_NEW_QSTR(MP_QSTR_log10), (mp_obj_t)&mp_math_log10_obj },
     { MP_OBJ_NEW_QSTR(MP_QSTR_cosh), (mp_obj_t)&mp_math_cosh_obj },
@@ -206,6 +207,7 @@
     { MP_OBJ_NEW_QSTR(MP_QSTR_acosh), (mp_obj_t)&mp_math_acosh_obj },
     { MP_OBJ_NEW_QSTR(MP_QSTR_asinh), (mp_obj_t)&mp_math_asinh_obj },
     { MP_OBJ_NEW_QSTR(MP_QSTR_atanh), (mp_obj_t)&mp_math_atanh_obj },
+    #endif
     { MP_OBJ_NEW_QSTR(MP_QSTR_cos), (mp_obj_t)&mp_math_cos_obj },
     { MP_OBJ_NEW_QSTR(MP_QSTR_sin), (mp_obj_t)&mp_math_sin_obj },
     { MP_OBJ_NEW_QSTR(MP_QSTR_tan), (mp_obj_t)&mp_math_tan_obj },