more texinfo 5.1 hacks

For hx509.texi, we need the copyright macros for both html and info.
Just remove the "ifhtml" conditionals.

For whatis.texi, texinfo 5.1 inserts the sub{} macro inline with no
newlines, so there are errors about @html not being at the end of a
line, etc.

doc/whatis.texi

@@ -43,9 +43,11 @@ services can authenticate each other.
 
 @ifhtml
 @macro sub{arg}
+
 @html
 <sub>\arg\</sub>
 @end html
+
 @end macro
 @end ifhtml