freestanding: add core linux syscalls and associated tests

vlib/builtin/bare/.checks/string/string.v

@@ -0,0 +1,15 @@
+module main
+
+fn check_string_eq () {
+	println ("checking string_eq")
+	assert "monkey" != "rat"
+	some_animal := "a bird"
+	assert some_animal == "a bird"
+	println ("string_eq passed")
+}
+
+fn main () {
+	check_string_eq ()
+	sys_exit(0)
+}
+