gitlab-ci: Move scons build/test commands to a separate shell script

Preparatory, no functional change intended.

Reviewed-by: Eric Engestrom <eric.engestrom@intel.com>

.gitlab-ci.yml

@@ -129,11 +129,7 @@ test-container:arm64:
   variables:
     SCONSFLAGS: "-j4"
   script:
-    - if test -n "$LLVM_VERSION"; then
-        export LLVM_CONFIG="llvm-config-${LLVM_VERSION}";
-      fi
-    - scons $SCONS_TARGET
-    - eval $SCONS_CHECK_COMMAND
+    - .gitlab-ci/scons-build.sh
 
 meson-main:
   extends:

.gitlab-ci/scons-build.sh

@@ -0,0 +1,12 @@
+#!/bin/bash
+
+set -e
+set -o xtrace
+
+if test -n "$LLVM_VERSION"; then
+    export LLVM_CONFIG="llvm-config-${LLVM_VERSION}"
+fi
+
+rm -rf build
+scons $SCONS_TARGET
+eval $SCONS_CHECK_COMMAND