Fix our missing abs/labs/llabs/imaxabs (and imaxdiv) symbols.

Change-Id: I94c411c22634e43184445c82e7388e51fc46a8cc
diff --git a/libc/include/stdlib.h b/libc/include/stdlib.h
index e728cb6..9fa84c1 100644
--- a/libc/include/stdlib.h
+++ b/libc/include/stdlib.h
@@ -77,17 +77,9 @@
     return (strtod(nptr, NULL));
 }
 
-static __inline__ int abs(int __n) {
-    return (__n < 0) ? -__n : __n;
-}
-
-static __inline__ long labs(long __n) {
-    return (__n < 0L) ? -__n : __n;
-}
-
-static __inline__ long long llabs(long long __n) {
-    return (__n < 0LL) ? -__n : __n;
-}
+extern int abs(int) __pure2;
+extern long labs(long) __pure2;
+extern long long llabs(long long) __pure2;
 
 extern char * realpath(const char *path, char *resolved);
 extern int system(const char * string);