all.sh: move clang_version() to helpers file

This function is only used in (a few) components, it's not part of the core.

Signed-off-by: Manuel Pégourié-Gonnard <manuel.pegourie-gonnard@arm.com>
diff --git a/tests/scripts/all-helpers.sh b/tests/scripts/all-helpers.sh
index b165042..de7c078 100644
--- a/tests/scripts/all-helpers.sh
+++ b/tests/scripts/all-helpers.sh
@@ -249,3 +249,11 @@
         "$ARMC6_FROMELF" -z ${BUILTIN_SRC_PATH}/*.o
     fi
 }
+
+clang_version() {
+    if command -v clang > /dev/null ; then
+        clang --version|grep version|sed -E 's#.*version ([0-9]+).*#\1#'
+    else
+        echo 0  # report version 0 for "no clang"
+    fi
+}
diff --git a/tests/scripts/all.sh b/tests/scripts/all.sh
index 0ceb1bf..b19199e 100755
--- a/tests/scripts/all.sh
+++ b/tests/scripts/all.sh
@@ -858,14 +858,6 @@
     fi
 }
 
-clang_version() {
-    if command -v clang > /dev/null ; then
-        clang --version|grep version|sed -E 's#.*version ([0-9]+).*#\1#'
-    else
-        echo 0  # report version 0 for "no clang"
-    fi
-}
-
 pre_load_helpers () {
     # The path is going to change when this is moved to the framework
     test_script_dir="${0%/*}"