scripts: speedup prohibit-duplicate-header

Running regular expressions with capture groups is expensive.
Bail out early if the line does not start with a '#'.

This reduces the runtime of the check by two thirds.

Signed-off-by: Ján Tomko <jtomko@redhat.com>
Reviewed-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Reviewed-by: Erik Skultety <eskultet@redhat.com>

scripts/prohibit-duplicate-header.py

@@ -30,6 +30,10 @@ def check_file(filename):
         for line in fh:
             lineno = lineno + 1
 
+            # skip non-matching lines early
+            if line[0] != '#':
+                continue
+
             headermatch = re.search(r'''^# *include *[<"]([^>"]*\.h)[">]''', line)
             if headermatch is not None:
                 inc = headermatch.group(1)