Add in the "_start" symbol in asm. Fix a makefile (that needs to be

abstracted I suppose for platforms (though I am doing fine w/o libcrt*)
and add function prototype for exit into stdlib.h (it was missing... odd).
Compiles vs uC-libc are less noisy now.
 -Erik

include/stdlib.h

@@ -14,6 +14,9 @@
 #define EXIT_FAILURE 1
 #define EXIT_SUCCESS 0
 
+extern void exit __P ((int __status)) __attribute__ ((__noreturn__));
+extern int atexit __P ((void (*__func) (void)));
+
 extern void * malloc __P ((size_t));
 extern void * calloc __P ((size_t, size_t));
 extern void free __P ((void *));