Android: clean only objects, not the folders

Some users building with a high number of threads
reported to me problems regarding the import_includes folder.

So, only delete objects files (.o) and keep import_includes

Change-Id: Ibf3ac818ff2bcf00bdf4f5243112001e2b2e15ef
Android: typo in busybox folder

That was a remains of a test when the folder doesnt exists

Change-Id: If1989dc774ae7c6a8a94692ada6c321f67b5f4d9
dmesg: rework color feature, compat. with more

when used with less or more, the colors were not in
the same buffer, resulting blocs of colors.

Also, reset color numbers to the 16 ANSI ones.

Reduce the diff with busybox to be able to send the patch.
This is the first full busybox aosp feature with the new build system

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

Change-Id: Ia0239a0bea02da01cae15736150dfee4fe66dcdb
Android.mk: toggle l-preview config flag

Change-Id: I4465b88a0337f5f267d501a94b2f71f8ef07b318
Test some tty related applets (getty, login, su)

and passwd, mkpasswd, cryptpw

Change-Id: I96ee64f0872856fad6b3ff299faafad6451da556