editline/history.h and editline/readline.h not found/working on OSX when trying to compile with developer tools installed already

Include only

#include <editline/readline.h>

which should exist if the command line tools are installed. This file contains the "readline wrapper" for libedit, including the history functions as well. An include file <editline/history.h> does not exist on OS X.

I tested your code with that modification, and it compiled and ran without problems.

Using OSX Yosemite. I removed #include<editline/history.h>

and then used cc -std=c99 -Wall test.c -ledit -o test

Works fine now

I'm on El Capitan, Remove #include <editline/history.h>, and use cc -std=c99 -Wall test.c -ledit -o test works for me.
Add the flag -ledit before the output flad, it's a linking process, allows the compiler to directly embed calls to editline in your program. Or, you'll get the below error message,

Undefined symbols for architecture x86_64:
  "_add_history", referenced from:
      _main in prompt-086f90.o
  "_readline", referenced from:
      _main in prompt-086f90.o
ld: symbol(s) not found for architecture x86_64