Remove all traces of HAVE_STRERROR.

The removal of strerror.c led to the function check being removed from
configure.in.
diff --git a/Modules/main.c b/Modules/main.c
index e6409e8..0cd879d 100644
--- a/Modules/main.c
+++ b/Modules/main.c
@@ -539,13 +539,9 @@
 
 		if (sts==-1 && filename!=NULL) {
 			if ((fp = fopen(filename, "r")) == NULL) {
-#ifdef HAVE_STRERROR
 				fprintf(stderr, "%s: can't open file '%s': [Errno %d] %s\n",
 					argv[0], filename, errno, strerror(errno));
-#else
-				fprintf(stderr, "%s: can't open file '%s': Errno %d\n",
-					argv[0], filename, errno);
-#endif
+
 				return 2;
 			}
 			else if (skipfirstline) {