[lk][tools] Fix a small error in the buildall script.
[lk][tools] Fix a small error in the buildall script.

Make use of the -j level which was computed in the script instead of
hardcoding to -j4

Change-Id: I99bf175709d1a2c8757fe73a7ddbb6361d431e69
Signed-off-by: John Grossman <44f967844db7503dcc298cd6e9847cf97867f9b6@google.com>

littlekernel/lk,sndnvaps/lk,GCrean/lk,travisg/lk,nvll/lk,srodrig1/lk,minglun-tsai/lk,hollanderic/lkstuff,hollanderic/lkstuff,nvll/lk,travisg/lk,srodrig1/lk,GCrean/lk,nvll/lk,srodrig1/lk,skabet/lk,sndnvaps/lk,skabet/lk,nvll/lk,minglun-tsai/lk,skabet/lk,minglun-tsai/lk,sndnvaps/lk,GCrean/lk,skabet/lk,GCrean/lk,GCrean/lk,travisg/lk,minglun-tsai/lk,srodrig1/lk,littlekernel/lk,hollanderic/lkstuff,travisg/lk,ErikCorryGoogle/lk,ErikCorryGoogle/lk,littlekernel/lk,ErikCorryGoogle/lk,skabet/lk,littlekernel/lk,nvll/lk,ErikCorryGoogle/lk,srodrig1/lk,hollanderic/lkstuff,sndnvaps/lk,sndnvaps/lk