Use S3 dispatch for integer64 methods (#7753)

Author: MichaelChirico

inst/tests/tests.Rraw

@@ -9443,7 +9443,7 @@ construct <- function(cols, vals, ops, x, y) {
   expr = lapply(seq_along(cols), function(i) {
     GT_or_LT = ops[i]==">" || ops[i]=="<"
     if (inherits(vals[[i]], "integer64")) {
-      if (is.na.integer64(vals[[i]])) if (GT_or_LT) quote(logical()) else as.call(list(quote(is.na.integer64), as.name(cols[[i]])))
+      if (is.na(vals[[i]])) if (GT_or_LT) quote(logical()) else as.call(list(quote(is.na), as.name(cols[[i]])))
       else as.call(list(as.name(ops[[i]]), as.name(cols[[i]]), as.integer(vals[[i]])))
       # don't know how to construct a call with int64 -- vals[[i]] gets converted to NAN
     } else {