ionice: fix missing syscall and add the applet

with the help of Tias Guns <tias@ulyssis.org>

PS: not symlinked, we have /system/bin/ionice in android toolbox
    its included as an alternative

Change-Id: Ib01023fb083a5b55467f52cd303eeaa8a9405a1d
diff --git a/include/android.h b/include/android.h
index 8599416..4463635 100644
--- a/include/android.h
+++ b/include/android.h
@@ -29,16 +29,17 @@
 /* defined in bionic/stubs.c */
 char *ttyname(int);
 
-/* added to SYSCALLS.TXT:
-int    stime(time_t *) 25
-int    swapon(const char *, int)       87
-int    swapoff(const char *)   115
-*/
+/* SYSCALLS */
 int    stime(time_t *);
 int    swapon(const char *, int);
 int    swapoff(const char *);
 int    getsid(pid_t);
 
+#ifndef SYS_ioprio_set
+#define SYS_ioprio_set __NR_ioprio_set
+#define SYS_ioprio_get __NR_ioprio_get
+#endif
+
 /* local definition in libbb/xfuncs_printf.c */
 int fdprintf(int fd, const char *format, ...);