Add backtrace-based error path testing mechanism

Add backtrace-based error path testing mechanism

The new TEST_FAIL and GET_FAIL control interface commands can be used
similarly to the earlier TEST_ALLOC_FAIL/GET_ALLOC_FAIL design. The new
version is more generic framework allowing any function to be annotated
for failure testing with the TEST_FAIL() macro. This mechanism is only
available in builds with CONFIG_WPA_TRACE_BFD=y and
CONFIG_TESTING_OPTIONS=y. For other builds, the TEST_FAIL() macro is
defined to return 0 to allow the compiler to remove the test code from
normal production builds.

As the first test site, allow os_get_random() to be marked for failing
based on call backtrace.

Signed-off-by: Jouni Malinen <j@w1.fi>