makesyscalls.lua: Allow translation of intptr_t arguments

Translate instances of intptr_t to the config value abi_intptr_t
(defaults to "intptr_t").  Used in CheriABI to translate intptr_t
to intcap_t for hybrid kernels.

Reviewed by:	kevans

sys/tools/makesyscalls.lua

@@ -61,6 +61,7 @@ local config = {
 	abi_flags = "",
 	abi_flags_mask = 0,
 	abi_headers = "",
+	abi_intptr_t = "intptr_t",
 	ptr_intptr_t_cast = "intptr_t",
 }
 
@@ -398,9 +399,11 @@ local function write_line_pfile(tmppat, line)
 	end
 end
 
+-- Check both literal intptr_t and the abi version because this needs
+-- to work both before and after the substitution
 local function isptrtype(type)
 	return type:find("*") or type:find("caddr_t") or
-	    type:find("intptr_t")
+	    type:find("intptr_t") or type:find(config['abi_intptr_t'])
 end
 
 local process_syscall_def
@@ -599,6 +602,8 @@ local function process_args(args)
 			goto out
 		end
 
+		argtype = argtype:gsub("intptr_t", config["abi_intptr_t"])
+
 		-- XX TODO: Forward declarations? See: sysstubfwd in CheriBSD
 		if abi_change then
 			local abi_type_suffix = config["abi_type_suffix"]