Fix the no-comp option for Windows

no-comp on Windows was not actually suppressing compilation of the code,
although it was suppressing its use.

Reviewed-by: Richard Levitte <levitte@openssl.org>

crypto/comp/comp.h

@@ -4,6 +4,10 @@
 
 # include <openssl/crypto.h>
 
+# ifdef OPENSSL_NO_COMP
+#  error COMP is disabled.
+# endif
+
 #ifdef  __cplusplus
 extern "C" {
 #endif