Clean up featuresutils library

dlclose the featureutils library when closing the driver.
Had tried closing inside load_angle but that won't work
due to threading and we will have a featureutil resource
we want to keep around.

Bug: 118613436
Bug: 118375731
Test: monkey UI testing
Test: cts-tradefed run singleCommand cts -m CtsAngleIntegrationHostTestCases

Change-Id: I40b13c679665951935f0e7254f24c384645365f3