Fix update-doxygen, which fails when skia-autogen is reset

static_footer.txt was removed from skia/docs in r2837, but update-doxygen.sh
requires it to exist in skia-autogen.  If skia-autogen is cleared (frequently),
then static_footer.txt can't be found.  Add it back to trunk/tools and manually
copy it if needed.
Review URL: https://codereview.appspot.com/6568054

git-svn-id: http://skia.googlecode.com/svn/trunk@5694 2bbb7eff-a529-9590-31e7-b0007b416f81

tools/doxygen_footer.txt

@@ -0,0 +1,9 @@
+<!--
+  This is the static footer that Doxygen appends to every page.
+  It is not properly formed html; it must end with unbalanced /body
+  and /html tags.
+-->
+<hr class="footer"/>
+<iframe src="../iframe_footer.html" width="100%" frameborder=0></iframe>
+</body>
+</html>

tools/update-doxygen.sh

@@ -30,6 +30,10 @@ if [ -d "docs" ]; then
   svn update --accept theirs-full docs
 else
   svn checkout https://skia-autogen.googlecode.com/svn/docs  # writeable
+if [ ! -f "docs/static_footer.txt" ]; then
+  TOOLS_DIR="$(cd "$(dirname "$0" )" && pwd )"
+  cp ${TOOLS_DIR}/doxygen_footer.txt docs/static_footer.txt
+fi
 fi
 
 # Run Doxygen.