tinycap: Accept -T parameter for a timeout time.

Add an option to tinycap to specify a timeout for the audio
capture in seconds.

Bug: 63353429
Test: Capture stops automatically after the given timeout.
      Capture goes until interrupt signal when the timeout isn't
      specified.
Change-Id: I81101e308e9dac651e3f2c6a63e32483a0d63f92