android: fix building errors with Android L

Tested OK with Android L PDK LRW17D.

The asm files are regenerated by Android L gensyscalls.py.

syscalls: restore compatibilty with current branch

on arm __NR_stime constant is undefined in asm/unistd.h

add also BIONIC_L define for assembly files (syscalls)
tested on arm and x86 (not on mips)

Signed-off-by: Tanguy Pruvot <tanguy.pruvot@gmail.com>

Change-Id: If5b6a6d3f8b4c10339f8e7b0bf340d02c1cf26cb
android: remove syscalls implemented in libbb

We missed the addition of libbb/missing_syscalls.c in 1.21

This also fix 'busybox date -s "2014-08-06 14:15:15"'
(tested in recovery too)

Change-Id: I2a1297e894638f000734b15757100c2d48984ed3