makeparallel: improve support for wrapping ninja

Allow makeparallel to pass better -j and -k arguments to ninja if the
first argument to makeparallel is --ninja.  Uses getopt to parse
MAKEFLAGS to get values for --jobserver-fds, -k, and -j, and uses the
result to not pass any -j argument to ninja for make -j with no number,
and pass -k0 to ninja for make -k.

Also improve the test makefile to provide many more tests.

Bug: 24199503
Change-Id: Id6481430f77e9e952213be58a98fe78c46ee5d6a