Move the executable part of checkIncludes.py inside an if block.

I'll want to make this block into a series of functions in a
subsequent commit, but I'm doing this separately to get the
indentation change out of the way.

This branch will end up with making checkIncludes.py an integrated
part of practracker, for ticket 31176.

scripts/maint/checkIncludes.py

@@ -134,48 +134,49 @@ def load_include_rules(fname):
             result.addPattern(line)
     return result
 
-list_unused = False
-log_sorted_levels = False
-
-uses_dirs = { }
-
-for dirpath, dirnames, fnames in os.walk("src"):
-    if ".may_include" in fnames:
-        rules = load_include_rules(os.path.join(dirpath, RULES_FNAME))
-        for fname in fnames:
-            if fname_is_c(fname):
-                rules.applyToFile(os.path.join(dirpath,fname))
-        if list_unused:
-            rules.noteUnusedRules()
-
-        uses_dirs[rules.incpath] = rules.getAllowedDirectories()
-
-if trouble:
-    err(
-"""To change which includes are allowed in a C file, edit the {}
-files in its enclosing directory.""".format(RULES_FNAME))
-    sys.exit(1)
-
-all_levels = []
-
-n = 0
-while uses_dirs:
-    n += 0
-    cur_level = []
-    for k in list(uses_dirs):
-        uses_dirs[k] = [ d for d in uses_dirs[k]
-                         if (d in uses_dirs and d != k)]
-        if uses_dirs[k] == []:
-            cur_level.append(k)
-    for k in cur_level:
-        del uses_dirs[k]
-    n += 1
-    if cur_level and log_sorted_levels:
-        print(n, cur_level)
-    if n > 100:
-        break
-
-if uses_dirs:
-    print("There are circular .may_include dependencies in here somewhere:",
-          uses_dirs)
-    sys.exit(1)
+if __name__ == '__main__':
+    list_unused = False
+    log_sorted_levels = False
+
+    uses_dirs = { }
+
+    for dirpath, dirnames, fnames in os.walk("src"):
+        if ".may_include" in fnames:
+            rules = load_include_rules(os.path.join(dirpath, RULES_FNAME))
+            for fname in fnames:
+                if fname_is_c(fname):
+                    rules.applyToFile(os.path.join(dirpath,fname))
+            if list_unused:
+                rules.noteUnusedRules()
+
+            uses_dirs[rules.incpath] = rules.getAllowedDirectories()
+
+    if trouble:
+        err(
+    """To change which includes are allowed in a C file, edit the {}
+    files in its enclosing directory.""".format(RULES_FNAME))
+        sys.exit(1)
+
+    all_levels = []
+
+    n = 0
+    while uses_dirs:
+        n += 0
+        cur_level = []
+        for k in list(uses_dirs):
+            uses_dirs[k] = [ d for d in uses_dirs[k]
+                             if (d in uses_dirs and d != k)]
+            if uses_dirs[k] == []:
+                cur_level.append(k)
+        for k in cur_level:
+            del uses_dirs[k]
+        n += 1
+        if cur_level and log_sorted_levels:
+            print(n, cur_level)
+        if n > 100:
+            break
+
+    if uses_dirs:
+        print("There are circular .may_include dependencies in here somewhere:",
+              uses_dirs)
+        sys.exit(1)