vim-patch:8.1.1803: all builtin functions are global

Problem:    All builtin functions are global.
Solution:   Add the method call operator ->.  Implemented for a limited number
            of functions.
ac92e25a33

- Note that to *exactly* port hunk @@ -7376,18 +7444,19 from
  handle_subscript(), we need the :scriptversion patches (I have an open
  PR for those, but this patch works fine without them anyway).
- Port call_internal_func() from v7.4.2058.
- Adjust some error messages in tests, as they rely on the Blob patches.
- Add a modeline to test_method.vim.

Ignore the global_functions and base_method tables and prefer the
current GPerf implementation. Instead, add an extra base_arg field to
VimLFuncDef that holds the number of the argument to use as the base
(1-indexed, so that 0 may be used to refer to functions that cannot be
used as methods).

This also means we support using any argument as a base from the get-go,
rather than just the first (Vim includes this ability in future patches,
however).

To mark a function as usable as a method, use the "base" key as
described in eval.lua.

src/nvim/generators/gen_eval.lua

@@ -42,7 +42,7 @@ gperfpipe:write([[
 %language=ANSI-C
 %global-table
 %readonly-tables
-%define initializer-suffix ,0,0,NULL,NULL
+%define initializer-suffix ,0,0,0,NULL,NULL
 %define word-array-name functions
 %define hash-function-name hash_internal_func_gperf
 %define lookup-function-name find_internal_func_gperf
@@ -59,9 +59,10 @@ for name, def in pairs(funcs) do
   elseif #args == 1 then
     args[2] = 'MAX_FUNC_ARGS'
   end
+  local base = def.base or 0
   local func = def.func or ('f_' .. name)
   local data = def.data or "NULL"
-  gperfpipe:write(('%s,  %s, %s, &%s, (FunPtr)%s\n')
-                  :format(name, args[1], args[2], func, data))
+  gperfpipe:write(('%s,  %s, %s, %s, &%s, (FunPtr)%s\n')
+                  :format(name, args[1], args[2], base, func, data))
 end
 gperfpipe:close()