checkpatch: check for SPDX tags of licenses in use

Fix the patch of the external helper spdxcheck.py accordingly to
OpenOCD folder structure.
List only the current LICENSES subfolders in spdxcheck.py .
Enable the check for SPDX headers.
Extend the check for TCL and Makefile.am files.

Change-Id: I0a40da0127746217ee0ac416058d5ceb922428ff
Signed-off-by: Antonio Borneo <borneo.antonio@gmail.com>
Reviewed-on: https://review.openocd.org/c/openocd/+/5608
Tested-by: jenkins

tools/scripts/spdxcheck.py

@@ -49,7 +49,9 @@ def read_spdxdata(repo):
 
     # The subdirectories of LICENSES in the kernel source
     # Note: exceptions needs to be parsed as last directory.
-    license_dirs = [ "preferred", "dual", "deprecated", "exceptions" ]
+    # OpenOCD specific: Begin
+    license_dirs = [ "preferred", "stand-alone", "exceptions" ]
+    # OpenOCD specific: End
     lictree = repo.head.commit.tree['LICENSES']
 
     spdx = SPDXdata()