Add ossl_inline

Add macro ossl_inline for use in public headers where a portable inline
is required. Change existing inline to use ossl_inline

Reviewed-by: Kurt Roeckx <kurt@openssl.org>

test/constant_time_test.c

@@ -45,6 +45,7 @@
  */
 
 #include "internal/constant_time_locl.h"
+#include "e_os.h"
 
 #include <limits.h>
 #include <stdio.h>