symb: Remove FB_SYMBSTATS_CALLED, use FB_SYMBSTATS_ACCESSED instead
ast: Clean up some unnecessary FB_DATATYPE_INVALID's in astNewARG() calls
symb: Let symbAddProcParam() call symbCalcProcParamLen() automatically

instead of calculating the size manually everytime.
Fix va_first() on BYVAL non-trivial UDT param (which is BYREF implicitly)

symbCalcParamLen() does not include the check for BYVAL non-trivial UDTs,
while symbCalcProcParamLen() (which is used to set a PARAM's FBSYMBOL.lgt
field) does.
symb: Round PARAM length when adding the param already

Since a PARAM symbol's FBSYMBOL.lgt field is used to hold the "real"
length (i.e. taking into account the BYVAL/BYREF/... mode, and special
cases), we may aswell always store the rounded size already too.
cParameters(): Replace symbCalcProcParamLen() with quicker symbGetLen()

For PARAM symbols, the length is already precalculated using
symbCalcProcParamLen(), so we can just reuse that here.
symb: Move FB_ROUNDLEN()'s into symbCalcProcParamLen()
symb: Move FB_ROUNDLEN()'s into symbCalcParamLen()
symb: Change symbCalc[Proc]ParamLen() to symbCalc{Arg|Param}Len()
symb: Remove iif() from symbGetLen(), it's never called on NULL