cygwin: use CREATE_DEFAULT_ERROR_MODE in spawn

This allows native processes to get Windows-default error handling
behavior (such as invoking the registered JIT debugger), while cygwin
processes would quickly set their error mode back to what they expect.

winsup/cygwin/spawn.cc

@@ -445,7 +445,8 @@ child_info_spawn::worker (const char *prog_arg, const char *const *argv,
       c_flags = GetPriorityClass (GetCurrentProcess ());
       sigproc_printf ("priority class %d", c_flags);
 
-      c_flags |= CREATE_SEPARATE_WOW_VDM | CREATE_UNICODE_ENVIRONMENT;
+      c_flags |= CREATE_SEPARATE_WOW_VDM | CREATE_UNICODE_ENVIRONMENT
+	      | CREATE_DEFAULT_ERROR_MODE;
 
       /* We're adding the CREATE_BREAKAWAY_FROM_JOB flag here to workaround
 	 issues with the "Program Compatibility Assistant (PCA) Service".