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/cmakeprojectmanager/cmakebuildconfiguration.h

@@ -63,6 +63,7 @@ public:
     QString warning() const;
 
     QStringList buildTargetTitles() const;
+    const QList<CMakeBuildTarget> &buildTargets() const;
     ProjectExplorer::BuildTargetInfoList appTargets() const;
     ProjectExplorer::DeploymentData deploymentData() const;
 
@@ -72,7 +73,6 @@ public:
 
     // Context menu action:
     void buildTarget(const QString &buildTarget);
-
 signals:
     void errorOccured(const QString &message);
     void warningOccured(const QString &message);
@@ -104,6 +104,7 @@ private:
     void setWarning(const QString &message);
 
     CMakeConfig m_configurationForCMake;
+    CMakeConfig m_initialConfiguration;
     QString m_error;
     QString m_warning;