Issue #300: Some platforms, such as MinGW, don't have ETXTBSY and ENOTBLK, so skip those there.

tests/strerror_override.c

@@ -24,7 +24,9 @@ static struct {
 	ENTRY(ENOMEM),
 	ENTRY(EACCES),
 	ENTRY(EFAULT),
+#ifdef ENOTBLK
 	ENTRY(ENOTBLK),
+#endif
 	ENTRY(EBUSY),
 	ENTRY(EEXIST),
 	ENTRY(EXDEV),
@@ -35,7 +37,9 @@ static struct {
 	ENTRY(ENFILE),
 	ENTRY(EMFILE),
 	ENTRY(ENOTTY),
+#ifdef ETXTBSY
 	ENTRY(ETXTBSY),
+#endif
 	ENTRY(EFBIG),
 	ENTRY(ENOSPC),
 	ENTRY(ESPIPE),