wolfssl: Avoid conflict with RNG when built without EdDSA or FIPS enabled

There are definitions of RNG in <wolfssl/wolfcrypt/settings.h> and
<wolfssl/wolfcrypt/random.h> that play havoc with the literal RNG being
used in the expansions of PLUGIN_*(RNG, ...) when ##-concatenated to
build the enum value FEATURE_RNG.

The #undef in wolfssl_cmmon.h only had an effect if wolfSSL was built
with EdDSA or FIPS enabled, otherwise, the headers that define RNG were
not pulled in before it.

Signed-off-by: Philip Prindeville <philipp@redfish-solutions.com>

src/libstrongswan/plugins/wolfssl/wolfssl_common.h

@@ -80,7 +80,4 @@ typedef union {
 
 #undef PARSE_ERROR
 
-/* Eliminate macro conflicts */
-#undef RNG
-
 #endif /* WOLFSSL_PLUGIN_COMMON_H_ */

src/libstrongswan/plugins/wolfssl/wolfssl_plugin.c

@@ -47,6 +47,8 @@
 
 #include <wolfssl/ssl.h>
 
+#undef RNG
+
 #ifndef FIPS_MODE
 #define FIPS_MODE 0
 #endif