fix/build_package: workspace cleanup when jenkins ci is not set

When `jenkins_run` is not set workspace is cleaned up either if
`dont_clean` flag is set. This removes any previous file storage
in the workspace which may cause the job to fail.

Signed-off-by: Leandro Belli <leandro.belli@arm.com>
Change-Id: I740ef5c06e0734ea424d0d4c959ada24b6cde61e
diff --git a/script/build_package.sh b/script/build_package.sh
index 07d878d..e165da6 100755
--- a/script/build_package.sh
+++ b/script/build_package.sh
@@ -1135,7 +1135,7 @@
 }
 
 # Clear workspace for a local run
-if not_upon "$jenkins_run"; then
+if not_upon "$jenkins_run" && not_upon "$dont_clean"; then
 	rm -rf "$workspace"
 
 	# Clear residue from previous runs