scripts: check-symfile: Allow also symbols in 'readonly' section

Validate also variables exported as 'extern' e.g. from the util
submodule.

Signed-off-by: Peter Krempa <pkrempa@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>

scripts/check-symfile.py

@@ -61,7 +61,7 @@ for elflib in elflibs:
 
     for line in nm:
         line = line.decode("utf-8")
-        symmatch = re.search(r'''^\S+\s(?:[TBSDG])\s(\S+)\s*$''', line)
+        symmatch = re.search(r'''^\S+\s(?:[TBSDGR])\s(\S+)\s*$''', line)
         if symmatch is None:
             continue