all.sh: Enable verbose failure messages for CMake

Set the CMake-observed variable `CTEST_OUTPUT_ON_FAILURE`, so that when
a "make test" run by CMake fails, verbose test output about the detail
of failure is available.

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
diff --git a/tests/scripts/all.sh b/tests/scripts/all.sh
index fad539a..45765b2 100755
--- a/tests/scripts/all.sh
+++ b/tests/scripts/all.sh
@@ -185,6 +185,9 @@
         export MAKEFLAGS="-j"
     fi
 
+    # Include more verbose output for failing tests run by CMake
+    export CTEST_OUTPUT_ON_FAILURE=1
+
     # CFLAGS and LDFLAGS for Asan builds that don't use CMake
     ASAN_CFLAGS='-Werror -Wall -Wextra -fsanitize=address,undefined -fno-sanitize-recover=all'