Fix inconsistent equalfuncs.c behavior for FuncCall.funcformat.

Other equalfuncs.c checks on CoercionForm fields use
COMPARE_COERCIONFORM_FIELD (which makes them no-ops),
but commit 40c24bfe neglected to make _equalFuncCall
do likewise.  Fix that.

This is only strictly correct if FuncCall.funcformat has
no semantic effect, instead just determining ruleutils.c
display formatting.  40c24bfe added a couple of checks
in parse analysis that could break that rule; but on closer
inspection, they're redundant, so just take them out again.

Per report from Noah Misch.

Discussion: https://postgr.es/m/20210606063331.GC297923@rfd.leadboat.com

src/backend/nodes/equalfuncs.c

@@ -2420,7 +2420,7 @@ _equalFuncCall(const FuncCall *a, const FuncCall *b)
 	COMPARE_SCALAR_FIELD(agg_star);
 	COMPARE_SCALAR_FIELD(agg_distinct);
 	COMPARE_SCALAR_FIELD(func_variadic);
-	COMPARE_SCALAR_FIELD(funcformat);
+	COMPARE_COERCIONFORM_FIELD(funcformat);
 	COMPARE_LOCATION_FIELD(location);
 
 	return true;

src/backend/parser/parse_clause.c

@@ -543,7 +543,6 @@ transformRangeFunction(ParseState *pstate, RangeFunction *r)
 				!fc->agg_star &&
 				!fc->agg_distinct &&
 				!fc->func_variadic &&
-				fc->funcformat == COERCE_EXPLICIT_CALL &&
 				coldeflist == NIL)
 			{
 				ListCell   *lc;

src/backend/parser/parse_func.c

@@ -222,7 +222,6 @@ ParseFuncOrColumn(ParseState *pstate, List *funcname, List *fargs,
 						   agg_order == NIL && agg_filter == NULL &&
 						   !agg_star && !agg_distinct && over == NULL &&
 						   !func_variadic && argnames == NIL &&
-						   funcformat == COERCE_EXPLICIT_CALL &&
 						   list_length(funcname) == 1 &&
 						   (actual_arg_types[0] == RECORDOID ||
 							ISCOMPLEX(actual_arg_types[0])));