Remove unnecessary 'extern's.

Change-Id: Iba2b3fb6ff88e504f1657b915120ae43d58a1e03
diff --git a/libc/include/sys/ipc.h b/libc/include/sys/ipc.h
index c0ae0ba..99bc5db 100644
--- a/libc/include/sys/ipc.h
+++ b/libc/include/sys/ipc.h
@@ -25,6 +25,7 @@
  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  */
+
 #ifndef _SYS_IPC_H
 #define _SYS_IPC_H
 
@@ -34,7 +35,7 @@
 
 __BEGIN_DECLS
 
-extern key_t  ftok(const char*  path, int  id);
+key_t ftok(const char* path, int id);
 
 __END_DECLS