move !defined(EXTERNAL_OPTS_OPENVPN) assert from src/internal.c to wolfssl/wolfcrypt/types.h with refinements; refine logic+message of assert in wolfssl/wolfcrypt/settings.h re "wolfssl/options.h included in compiled wolfssl library object..".

src/internal.c

@@ -92,12 +92,6 @@
  *      pair
  */
 
-
-#ifdef EXTERNAL_OPTS_OPENVPN
-#error EXTERNAL_OPTS_OPENVPN should not be defined\
-    when building wolfSSL
-#endif
-
 #ifndef WOLFCRYPT_ONLY
 
 #include <wolfssl/internal.h>

wolfssl/wolfcrypt/settings.h

@@ -319,8 +319,10 @@
     #endif
 #endif
 
-#if defined(BUILDING_WOLFSSL) && defined(WOLFSSL_OPTIONS_H)
+#if (defined(BUILDING_WOLFSSL) && defined(WOLFSSL_USE_OPTIONS_H)) || \
-    #error wolfssl/options.h included in build of library object.
+    (defined(BUILDING_WOLFSSL) && defined(WOLFSSL_OPTIONS_H) &&      \
+     !defined(EXTERNAL_OPTS_OPENVPN))
+    #error wolfssl/options.h included in compiled wolfssl library object.
 #endif
 
 #ifdef WOLFSSL_USER_SETTINGS

wolfssl/wolfcrypt/types.h

@@ -34,6 +34,10 @@ decouple library dependencies with standard string, memory and so on.
     #include <wolfssl/wolfcrypt/settings.h>
     #include <wolfssl/wolfcrypt/wc_port.h>
 
+    #if defined(EXTERNAL_OPTS_OPENVPN) && defined(BUILDING_WOLFSSL)
+    #error EXTERNAL_OPTS_OPENVPN should not be defined in compiled wolfssl library files.
+    #endif
+
     #ifdef __APPLE__
         #include <AvailabilityMacros.h>
     #endif