Rely on e_os.h to appropriately define str[n]casecmp in non-POSIX
environments.
diff --git a/e_os.h b/e_os.h
index 79f76ca..3ff9f3c 100644
--- a/e_os.h
+++ b/e_os.h
@@ -556,6 +556,7 @@
 #  include "o_str.h"
 #  define strcasecmp OPENSSL_strcasecmp
 #  define strncasecmp OPENSSL_strncasecmp
+#  define OPENSSL_IMPLEMENTS_strncasecmp
 #elif defined(OPENSSL_SYS_OS2) && defined(__EMX__)
 #  define strcasecmp stricmp
 #  define strncasecmp strnicmp