fix finishswap stuck forever in sync fence

Turns out on nexus5, not setting the flush flag makes client wait
forever in the finishswap fence.
increase runtime of test_glesv2

It was discovered that a file descriptor leak on fbdev mode would
manifest in a frozen client after around 15s. Therefore increase runtime
of the test and make runtime configurable.
Merge pull request #232 from heeen/master

Two changes for EGL and gles