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/_fileio.c b/Modules/_fileio.c
index bf52707..00689b3 100644
--- a/Modules/_fileio.c
+++ b/Modules/_fileio.c
@@ -104,11 +104,7 @@
 	if (self->fd < 0)
 		return 0;
 	if (fstat(self->fd, &buf) == 0 && S_ISDIR(buf.st_mode)) {
-#ifdef HAVE_STRERROR
 		char *msg = strerror(EISDIR);
-#else
-		char *msg = "Is a directory";
-#endif
 		PyObject *exc;
 		internal_close(self);
 
@@ -295,12 +291,8 @@
 	if (self->fd >= 0 && self->closefd) {
 		errno = internal_close(self);
 		if (errno < 0) {
-#ifdef HAVE_STRERROR
 			PySys_WriteStderr("close failed: [Errno %d] %s\n",
                                           errno, strerror(errno));
-#else
-			PySys_WriteStderr("close failed: [Errno %d]\n", errno);
-#endif
 		}
 	}
 
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) {
diff --git a/Modules/posixmodule.c b/Modules/posixmodule.c
index fab44d6..f73b73e 100644
--- a/Modules/posixmodule.c
+++ b/Modules/posixmodule.c
@@ -6710,7 +6710,6 @@
 }
 #endif /* unsetenv */
 
-#ifdef HAVE_STRERROR
 PyDoc_STRVAR(posix_strerror__doc__,
 "strerror(code) -> string\n\n\
 Translate an error code to a message string.");
@@ -6730,7 +6729,6 @@
 	}
 	return PyString_FromString(message);
 }
-#endif /* strerror */
 
 
 #ifdef HAVE_SYS_WAIT_H
@@ -8510,9 +8508,7 @@
 #ifdef HAVE_UNSETENV
 	{"unsetenv",	posix_unsetenv, METH_VARARGS, posix_unsetenv__doc__},
 #endif
-#ifdef HAVE_STRERROR
 	{"strerror",	posix_strerror, METH_VARARGS, posix_strerror__doc__},
-#endif
 #ifdef HAVE_FCHDIR
 	{"fchdir",	posix_fchdir, METH_O, posix_fchdir__doc__},
 #endif
diff --git a/Modules/socketmodule.c b/Modules/socketmodule.c
index d5114e8..13354d0 100644
--- a/Modules/socketmodule.c
+++ b/Modules/socketmodule.c
@@ -3110,15 +3110,10 @@
 	}
 
 	if (h->h_addrtype != af) {
-#ifdef HAVE_STRERROR
 		/* Let's get real error message to return */
 		PyErr_SetString(socket_error,
 				(char *)strerror(EAFNOSUPPORT));
-#else
-		PyErr_SetString(
-			socket_error,
-			"Address family not supported by protocol family");
-#endif
+
 		return NULL;
 	}