Add "FIXME" comment.

crypto/asn1/a_utctm.c

@@ -291,5 +291,12 @@ time_t ASN1_UTCTIME_get(const ASN1_UTCTIME *s)
 		}
 #undef g2
 
-	return mktime(&tm)-offset*60;
+	return mktime(&tm)-offset*60; /* FIXME: mktime assumes the current timezone
+	                               * instead of UTC, and unless we rewrite OpenSSL
+				       * in Lisp we cannot locally change the timezone
+				       * without possibly interfering with other parts
+	                               * of the program. timegm, which uses UTC, is
+				       * non-standard.
+	                               * Also time_t is inappropriate for general
+	                               * UTC times because it may a 32 bit type. */
 	}