gitlab-ci: add scons llvm 3.5 build

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

.gitlab-ci.yml

@@ -116,6 +116,9 @@ containers:ubuntu:
   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
 
@@ -171,3 +174,10 @@ build:scons-nollvm:
   variables:
     SCONS_TARGET: "llvm=0"
     SCONS_CHECK_COMMAND: "scons llvm=0 check"
+
+build:scons-llvm:
+  extends: .scons-build
+  variables:
+    SCONS_TARGET: "llvm=1"
+    SCONS_CHECK_COMMAND: "scons llvm=1 check"
+    LLVM_VERSION: "3.9"