check-code: Add a ``checkfile`` function

The part of the code actually checking each file is moved in the
``checkfile`` function to allow external reuses.

contrib/check-code.py

@@ -133,14 +133,8 b' checks = ['
     ('test script', r'(.*/)?test-[^.~]*$', testfilters, testpats),
     ('c', r'.*\.c$', cfilters, cpats),
 ]
-
-if __name__ == "__main__":
-    if len(sys.argv) == 1:
-        check = glob.glob("*")
-    else:
-        check = sys.argv[1:]
-
-    for f in check:
+def checkfile(f):
+    """checks style and portability of a given file"""
         for name, match, filters, pats in checks:
             fc = 0
             if not re.match(match, f):
@@ -168,3 +162,13 b' if __name__ == "__main__":'
                     print " (too many errors, giving up)"
                     break
             break
+
+
+if __name__ == "__main__":
+    if len(sys.argv) == 1:
+        check = glob.glob("*")
+    else:
+        check = sys.argv[1:]
+
+    for f in check:
+        checkfile(f)