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
40c24bfef 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.
40c24bfef 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