Makefile: remove warnings on initial version check

Android.mk is using a SUBMAKE variable which is only
used to get busybox version as a CFLAG. This one has
the -s (--silent) makeflag. So ignore the KBUILD_OUTPUT
default value if this flag is present.

Change-Id: Ifcc11d148d6707a8c301b3d2ba0370b91215647e
Android.mk: toggle l-preview config flag

Change-Id: I4465b88a0337f5f267d501a94b2f71f8ef07b318
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)

Change-Id: If5b6a6d3f8b4c10339f8e7b0bf340d02c1cf26cb
Signed-off-by: Tanguy Pruvot <tanguy.pruvot@gmail.com>