fails to compile with support:appcompat-v7:21 - cannot find symbol R.layout.abc_action_bar_decor

[GoogleCodeExporter]

What steps will reproduce the problem?
1. edit module build.gradle to change from using 7:20 to 7:21:
    compile 'com.android.support:appcompat-v7:21.+'
2.  Try to build app (which uses APV) in Android Studio

What is the expected output? What do you see instead?
Expected it to compile successfully, as it did up until the above change.
Instead, got the error:
.../src/main/java/cx/hell/android/pdfview/AboutPDFViewActivity.java:29: error: 
cannot find symbol
        InputStream aboutHtmlInputStream = new BufferedInputStream(resources.openRawResource(R.layout.abc_action_bar_decor));
                                                                                                     ^
  symbol:   variable abc_action_bar_decor
  location: class layout

When I look in the resource folders for support:appcompat 7:20 vs. 7:21, the 
former has abc_action_bar_decor.xml while the latter doesn't. 

What version of the product are you using? On what operating system?
APV 0.4.0, I believe
Mac OSX 10.10.3

Please provide any additional information below.

Original issue reported on code.google.com by hutt...@gmail.com on 15 Aug 2015 at 7:29