Support more ways to pass -j/-k

In preparation to remove Make/makeparallel from soong_ui startup, we
need to preserve compatibility with the different ways that make
supports the -j option.

Nothing changes unless Make/makeparallel is removed from the startup.
Once that is removed, not specifying a -j value will be equivalent to
'-j' instead of '-j1', like Ninja. A value will also be supported when
specifying -k, like Ninja (though specifying it alone will be equivalent
to '-k 0').

Test: m -j blueprint_tools
Change-Id: I9d5d59bedd4f6e5cca76bdb4cd47e0b5b7d523f0

ui/build/Android.bp

@@ -37,6 +37,7 @@ bootstrap_go_package {
         "util.go",
     ],
     testSrcs: [
+        "config_test.go",
         "environment_test.go",
         "util_test.go",
         "proc_sync_test.go",