Add bionic-unit-tests-run-on-host special target

Allows running the tests linked with bionic .so on the host if host and
target are compatible. See more comments and usage limitation inlined.

make bionic-unit-tests-run-on-host should do build and run.

Change-Id: I5946fa72e009d324baa9da18f460294b3c1a615e
Signed-off-by: Pavel Chupin <pavel.v.chupin@intel.com>

Conflicts:
	tests/Android.mk

Conflicts:
	tests/Android.mk