pythongh-133895: correct values of cmath.cosh/sinh in case of overflows

This is a split-off pythongh-134995.

The C17 standard says (cis(y) is defined as cos(y) + i sin(y)):
* ccosh(+∞ + i0) returns +∞ + i0.
* ccosh(+∞ + iy) returns +∞ cis(y), for finite nonzero y.
and
* csinh(+∞ + i0) returns +∞ + i0.
* csinh(+∞ + iy) returns +∞ cis(y), for positive finite y.

So far values, computed for exceptions, aren't accessible from the
pure-Python world, yet we are trying to be correct in other places.  The
Lib/test/mathdata/cmath_testcases.txt has data points with correct
numbers (see cosh0032 and sinh0032).

Also, use AC magic for the rect() value.

Author: skirpichev

Modules/clinic/cmathmodule.c.h

@@ -438,6 +438,9 @@ cmath_cosh_impl(PyObject *module, Py_complex z)
         x_minus_one = z.real - copysign(1., z.real);
         r.real = cos(z.imag) * cosh(x_minus_one) * Py_MATH_E;
         r.imag = sin(z.imag) * sinh(x_minus_one) * Py_MATH_E;
+        if (isnan(r.imag)) {
+            r.imag = copysign(0., z.real*z.imag);
+        }
     } else {
         r.real = cos(z.imag) * cosh(z.real);
         r.imag = sin(z.imag) * sinh(z.real);
@@ -674,6 +677,9 @@ cmath_sinh_impl(PyObject *module, Py_complex z)
         x_minus_one = z.real - copysign(1., z.real);
         r.real = cos(z.imag) * sinh(x_minus_one) * Py_MATH_E;
         r.imag = sin(z.imag) * cosh(x_minus_one) * Py_MATH_E;
+        if (isnan(r.imag)) {
+            r.imag = copysign(0., z.imag);
+        }
     } else {
         r.real = cos(z.imag) * sinh(z.real);
         r.imag = sin(z.imag) * cosh(z.real);
@@ -972,7 +978,7 @@ cmath_polar_impl(PyObject *module, Py_complex z)
 static Py_complex rect_special_values[7][7];
 
 /*[clinic input]
-cmath.rect
+cmath.rect -> Py_complex_protected
 
     r: double
     phi: double
@@ -981,9 +987,9 @@ cmath.rect
 Convert from polar coordinates to rectangular coordinates.
 [clinic start generated code]*/
 
-static PyObject *
+static Py_complex
 cmath_rect_impl(PyObject *module, double r, double phi)
-/*[clinic end generated code: output=385a0690925df2d5 input=24c5646d147efd69]*/
+/*[clinic end generated code: output=74ff3d17585f3388 input=50e60c5d28c834e6]*/
 {
     Py_complex z;
     errno = 0;
@@ -1027,11 +1033,7 @@ cmath_rect_impl(PyObject *module, double r, double phi)
         z.imag = r * sin(phi);
         errno = 0;
     }
-
-    if (errno != 0)
-        return math_error();
-    else
-        return PyComplex_FromCComplex(z);
+    return z;
 }
 
 /*[clinic input]