Introduce libbuf analogous to toybuf but for use by lib/*.c. Change readfile() semantics to be able to read into an existing buffer, or malloc its own if that's NULL.
diff --git a/main.c b/main.c
index dd985b8..53f670d 100644
--- a/main.c
+++ b/main.c
@@ -20,7 +20,7 @@
 
 struct toy_context toys;
 union global_union this;
-char toybuf[4096];
+char toybuf[4096], libbuf[4096];
 
 struct toy_list *toy_find(char *name)
 {