This is as close as we'll get to "set -e" from bash. Makes the script
less verbose, and closer to the Linux and MacOS ones.

Bug: b/159633249
Change-Id: Ied7cdb5ab11b737fb21379be912393bbd838a40a
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/45968
Kokoro-Result: kokoro <noreply+kokoro@google.com>
Reviewed-by: Nicolas Capens <nicolascapens@google.com>
Tested-by: Antonio Maiorano <amaiorano@google.com>