HelloGL2 example with launch target.

CMake creates 3 targets:

> grep TARGET CMakeLists.txt 
    TARGET hellogl2-apk
    BASE_TARGET hellogl2
    LAUNCH_TARGET hellogl2-launch

hellogl2 simple library target (ALL)
hellogl2-apk target to create Android APK, since there is no INSTALL option in add_qt_android_apk hence APK will not be installed on device after APK created (ALL)
hellogl2-launch target to create Android APK, install it on device and launch Qt application

Examples

Run default build. Targets that belongs to ALL will be built: hellogl2, hellogl2-apk (but not helogl2-launch). I.e. build library hellogl2 and create APK (no install, no launch):

> build.py --toolchain android-ndk-r10e-api-19-armeabi-v7a-neon --config Release --verbose

Run build of the library only:

> build.py --toolchain android-ndk-r10e-api-19-armeabi-v7a-neon --config Release --verbose --target hellogl2

Run build of the library and create APK:

> build.py --toolchain android-ndk-r10e-api-19-armeabi-v7a-neon --config Release --verbose --target hellogl2-apk

Run build of the library, create APK, install it to device and launch:

> build.py --toolchain android-ndk-r10e-api-19-armeabi-v7a-neon --config Release --verbose --target hellogl2-launch