Switch from old-style ASSERT macro to new-style ASSERT_EQ,... macros.
Using new-style macros makes it easier to debug test failures
Fixes: https://github.com/libuv/libuv/issues/2974
PR-URL: https://github.com/libuv/libuv/pull/2221
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Richard Lau <riclau@uk.ibm.com>
Reviewed-By: Refael Ackermann <refack@gmail.com>
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>