parallel-tests: fix recheck* targets for non-GNU make. * lib/am/check.am (recheck recheck-html): Override AM_MAKEFLAGS to portably transport the TEST_LOGS settings through the recursive `make' invocations. Fixes parallel-tests9.test failure with Solaris make. * tests/parallel-tests9.test: Also ensure that the test summary is correct for `recheck'. Suggestion by Akim Demaille. Signed-off-by: Ralf Wildenhues <Ralf.Wildenhues@gmx.de>