Use __predict_false on some fortify methods.

Give the compiler some hints that these error conditions
are unlikely to occur in practice.

Change-Id: Ifaf7322a12120ef663c8315c1a18c2dcbe4bda23
Add tests for __strcpy_chk()

Change-Id: I5675d04fcd471732c1b87b83879a54fbcd27762e
fix unittests.

7e6ce1a3c52d8533fed92c143419fedb0c93988a fixed abort() to raise
SIGABRT rather than causing SIGSEGV. However, the unittests were
not updated.

Fix unittests.

Change-Id: I73db194127b9b9e9440358aa94273863765a736b