Remove OpenSSL warnings ignore

If we include OpenSSL in extern "C" blocks consistently, c++ warnings no
longer appear.  This means we can remove the special case from meson.

Tested: Code compiles when built locally on an ubuntu 22.04 system.

Change-Id: I5add4113b32cd88b7fdd874174c845425a7c287a
Signed-off-by: Ed Tanous <ed@tanous.net>
diff --git a/include/ossl_random.hpp b/include/ossl_random.hpp
index b392410..0e28944 100644
--- a/include/ossl_random.hpp
+++ b/include/ossl_random.hpp
@@ -2,7 +2,10 @@
 
 #include "logging.hpp"
 
+extern "C"
+{
 #include <openssl/rand.h>
+}
 
 #include <iostream>
 #include <limits>