Calls to the EGL API from different threads may exit without releasing
their current TLS storage. This patch adds a destructor to release
them if they have not been released already. Prevents memory leakage in
processes where many threads are created.

Bug b/63434079
Bug swiftshader:80

Test: cts-tradefed run commandAndExit  cts -m CtsMediaTestCases -t \
      android.media.cts.DecodeAccuracyTest
Change-Id: I6e94a6d04ce84b884571248ab89b3b1a4e71998b
Reviewed-on: https://swiftshader-review.googlesource.com/18328Tested-by: David Rim <davidrim@google.com>
Reviewed-by: Nicolas Capens <nicolascapens@google.com>