On some platforms (in particular, ARM/AArch64), the implementation
of AV_READ_TIME() may use a privileged instruction - in such
cases, benchmarking just fails with a SIGILL.
Instead of crashing, try executing AV_READ_TIME() once within
a region with the signal handler active, to allow gracefully
informing the user about the issue.
This matches the dav1d checkasm commit
95a192549a448b70d9542e840c4e34b60d09b093.
Signed-off-by: Martin Storsjö <martin@martin.st>
ac40c3bb07