Rethink the libc layout.

lang/cem/libcc.ansi/build.lua

@@ -33,7 +33,7 @@ for _, plat in ipairs(vars.plats) do
 		srcs = {
 			"+ctype_files",
 			"+ctype_tab",
-			"./src/core/*.c",
+			"./pure/string/*.c",
 			"./ctype/*.c",
 			"./errno/*.c",
 			"./locale/*.c",

lang/cem/libcc.ansi/pure/README.md

@@ -0,0 +1,3 @@
+This directory contains _only_ pure-code libc functions with no dependencies
+on anything other than other pure functions (for example: strcmp, div). There
+should be no reason why any platform won't want these in its libc.