Make sparrow build script exit upon error

The build (and the CI) can report failure if the build script can't be
finished with zero code.

Change-Id: I273e02a50c8af46ffbcdfeb74e6a6c9a78bebbd2

build-sparrow.sh

diff --git a/build-sparrow.sh b/build-sparrow.sh
index 3ccd25f..0304c47 100755
--- a/build-sparrow.sh
+++ b/build-sparrow.sh
@@ -36,6 +36,8 @@
 # TODO(sleffler): maybe add install-* scripts for necessary toolchains
 # TODO(sleffler): maybe import dependent simulators as needed: qemu, spike, renode
 
+set -e
+
 TARGET_ARCH=${1:-aarch64}
 EXTRA_INIT_ARGS=
 MACHINE=