Say hello to Android CMake support

Requirements:
 - NDKr19 or newer
 - Qt 5.12.1 or newer

QtCreator supports the following variables:
 - ANDROID_PACKAGE_SOURCE_DIR
 - ANDROID_EXTRA_LIBS

Be aware, that there is a lot of magic done on QtCreator side, and you
can't use only cmake to build an Android APK.

[ChangeLog][Android][CMake] Add Android support for CMake projects.

Change-Id: I1d351976ed56f424c2bc972f4ff7b5968147a2ed
Reviewed-by: hjk <hjk@qt.io>

src/plugins/android/androidpackageinstallationstep.cpp

@@ -68,6 +68,7 @@ bool AndroidPackageInstallationStep::init()
 
     ToolChain *tc = ToolChainKitAspect::toolChain(target()->kit(),
                                                        ProjectExplorer::Constants::CXX_LANGUAGE_ID);
+    QTC_ASSERT(tc, return false);
 
     ProcessParameters *pp = processParameters();
     pp->setMacroExpander(bc->macroExpander());