Cosmetic improvements/code cleanup:

- replace some function signatures of the form "some_type foo()" with
"some_type foo(void)"
- replace a few instances of a literal 0 being used as a NULL pointer;
there are more instances of this in the code, but I just fixed a few
- in src/backend/utils/mb/wstrncmp.c, replace K&R style function
declarations with ANSI style, remove use of 'register' keyword
- remove an "extern" modifier that was applied to a function definition
(rather than a declaration)

src/backend/utils/misc/guc.c

@@ -10,7 +10,7 @@
  * Written by Peter Eisentraut <peter_e@gmx.net>.
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/utils/misc/guc.c,v 1.241 2004/10/09 23:13:10 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/utils/misc/guc.c,v 1.242 2004/10/10 23:37:28 neilc Exp $
  *
  *--------------------------------------------------------------------
  */
@@ -4378,7 +4378,7 @@ DefineCustomStringVariable(
 	define_custom_variable(&var->gen);
 }
 
-extern void
+void
 EmitWarningsOnPlaceholders(const char *className)
 {
 	struct config_generic **vars = guc_variables;