bpo-38835: Don't use PyFPE_START_PROTECT and PyFPE_END_PROTECT (GH-17231)

The PyFPE_START_PROTECT() and PyFPE_END_PROTECT() macros are empty:
they have been doing nothing for the last year  (since commit
735ae8d139), so stop using them.

Python/pystrtod.c

@@ -342,9 +342,7 @@ PyOS_string_to_double(const char *s,
     char *fail_pos;
 
     errno = 0;
-    PyFPE_START_PROTECT("PyOS_string_to_double", return -1.0)
     x = _PyOS_ascii_strtod(s, &fail_pos);
-    PyFPE_END_PROTECT(x)
 
     if (errno == ENOMEM) {
         PyErr_NoMemory();