Android: support building Qt as a shadow build

For the last few weeks I've been starting with an empty directory and configuring the android build like this:

../qt5-stable/configure -developer-build -xplatform android-g++ -android-ndk /opt/android-ndk -android-sdk /opt/android-sdk -nomake tests -nomake examples -opensource -confirm-license -no-warnings-are-errors

(after having set the following environment variables:
ANDROID_HOME=/opt/android-sdk
ANDROID_SWT=/usr/share/java
ANDROID_NDK_ROOT=/opt/android-ndk
ANDROID_NDK_HOST=linux-x86_64
ANDROID_BUILD_TOOLS_REVISION=18.0.1
ANDROID_NDK_PLATFORM=android-14
ANDROID_TARGET_ARCH=armeabi-v7a
ANDROID_NDK_TOOLCHAIN_VERSION=4.8
ANDROID_NDK=/opt/android-ndk )

then I can type make and most of it gets built. qttools does not get built though, so then I have to do

mkcd qttools
../../qt5-stable/qttools
make

And then when trying to build and install an app from the command line, I run androiddeployqt and get this error:

Cannot find ./res/values/libs.xml in prepared packaged. This file is required.

It will be corrected if I go back to the qtbase shadow build dir and do "make install"; that installs too much, and reports some errors about replacing files that are already there, but the important thing is that we end up with qtbase/src/android/java/res/values/libs.xml, and some classes etc. under qtbase/src/android/java. But when building Qt for desktop platforms it's not necessary to do make install. So it would seem possible to install just the needed files when doing a shadow build (make with no arguments).