rudimentary documentation for the includebloat script

Change-Id: I52209b70b3d93e488e6c9d16fefd179f2ac06afb

bin/includebloat.awk

 #!/usr/bin/gawk -f
+# -*- tab-width: 4; indent-tabs-mode: t -*-
+#
+# This file is part of the LibreOffice project.
+#
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+#
+
+# Generate a list of files included by the C++ compiler during the build
+# sorted by the total bytes an included file contributed to preprocessor input.
+# usage: first do a full build with "make check", then run this from $BUILDDIR
+
+# NOTE: by default gbuild does not generate dependencies for system headers
+#    (in particular the C++ standard library), so those will NOT be counted
 
 BEGIN {
     cmd = "find workdir/Dep/CxxObject/ -name *.d | xargs cat"
@@ -27,8 +42,10 @@ END {
         close(cmd)
     }
     PROCINFO["sorted_in"] = "@val_num_desc"
-    print "sum total bytes included: " totalsize
+    print "sum total bytes included (excluding system headers): " totalsize
     for (inc in totals) {
         print totals[inc], sizes[inc], includes[inc], inc
     }
 }
+
+# vim: set noet sw=4 ts=4: