When detecting an invalid system configuration for overflow checks, at least...

When detecting an invalid system configuration for overflow checks, at least print a warning, instead of leaving a dangling live exception behind.

Cython/Utility/Overflow.c

@@ -47,8 +47,12 @@ static int __Pyx_check_twos_complement(void) {
 #define __Pyx_div_const_no_overflow(a, b, overflow) ((a) / (b))
 
 /////////////// Common.init ///////////////
+//@substitute: naming
 
-__Pyx_check_twos_complement();
+// FIXME: Propagate the error here instead of just printing it.
+if (unlikely(__Pyx_check_twos_complement())) {
+    PyErr_WriteUnraisable($module_cname);
+}
 
 /////////////// BaseCaseUnsigned.proto ///////////////
 
@@ -226,8 +230,12 @@ static CYTHON_INLINE {{INT}} __Pyx_div_{{NAME}}_checking_overflow({{INT}} a, {{I
 
 
 /////////////// SizeCheck.init ///////////////
+//@substitute: naming
 
-__Pyx_check_sane_{{NAME}}();
+// FIXME: Propagate the error here instead of just printing it.
+if (unlikely(__Pyx_check_sane_{{NAME}}())) {
+    PyErr_WriteUnraisable($module_cname);
+}
 
 /////////////// SizeCheck.proto ///////////////