add EQ unit test "unit/fi_eq_test"

start of test for #48
currently uses fi_eq_write() to generate events, but need to use alternate mechanism for providers that do not support it.

tests still needed:
- EQ groups
- FI_WAIT_UNSPEC
- FI_WAIT_MUTEX
- readerr testing
- multi-threaded stress

question:  should the output be more granular about what all is being tested, or ok to refer to source to make sure provider is comfortable with coverage?

Signed-off-by: Reese Faucette <rfaucett@cisco.com>
I wonder if it's worth clearing entry inside each loop to ensure that the same data is read on the peek and the read -- or use different entries for each call and do a memcmp?