Android: Pull the right libc.so from device.

On an 64 bit Android, libc.so for 64 bit apps is located in /system/lib64/.

Change-Id: I93f0e4658e552c9a32822706bab3e503642a8c59
Reviewed-by: Daniel Teske <daniel.teske@theqtcompany.com>

src/plugins/android/androiddeployqtstep.h

@@ -128,6 +128,7 @@ private:
     QString m_avdName;
     QString m_apkPath;
     QString m_appProcess;
+    QString m_libdir;
 
     QString m_targetArch;
     bool m_uninstallPreviousPackage;