Put analyze_keyword back in explain_option_name production.

In commit 2c92edad, I broke "EXPLAIN
(ANALYZE)" syntax, because I mistakenly thought that ANALYZE/ANALYSE were
only partially reserved and thus would be included in NonReservedWord;
but actually they're fully reserved so they still need to be called out
here.

A nicer solution would be to demote these words to type_func_name_keyword
status (they can't be less than that because of "VACUUM [ANALYZE] ColId").
While that works fine so far as the core grammar is concerned, it breaks
ECPG's grammar for reasons I don't have time to isolate at the moment.
So do this for the time being.

Per report from Kevin Grittner.  Back-patch to 9.0, like the previous
commit.

src/backend/parser/gram.y

@@ -8669,6 +8669,7 @@ explain_option_elem:
 
 explain_option_name:
 			NonReservedWord			{ $$ = $1; }
+			| analyze_keyword		{ $$ = "analyze"; }
 		;
 
 explain_option_arg: