Merge bitcoin/bitcoin#30049: build, test, doc: Temporarily remove Android-related stuff

5deb0b024e build, test, doc: Temporarily remove Android-related stuff (Hennadii Stepanov)

Pull request description:

  Previously, our Android builds were geared towards generating APKs, which relied on Qt. However, after migrating to C++20, compiling for Android became unfeasible due to Qt 5.15's compatibility limitations with NDK only up to r25, which includes an outdated embedded libc++ (see https://github.com/bitcoin/bitcoin/issues/29360).

  All removed stuff will be reinstated after migrating the build system to CMake and upgrading Qt to version 6.x.

  This PR makes possible a clean migration to the CMake-based build system as it removes code, which is not used at this moment.

ACKs for top commit:
  vasild:
    ACK 5deb0b024e
  fanquake:
    ACK 5deb0b024e - given none of this is currently tested/wont compile. Can be revisted in future.

Tree-SHA512: 3bc2ccfe881e11cc1d78c27acd6f1d86cfba86821ef3bb5eca2e80d978fdfa13659ec82284dcaadc507e2394524dea91d4b8f81d0030c1cef9708df8be76bf07

build-aux/m4/bitcoin_qt.m4

@@ -70,8 +70,6 @@ AC_DEFUN([BITCOIN_QT_INIT],[
                  [qt_lib_suffix= ]); bitcoin_qt_want_version=qt5],
         [qt_lib_suffix= ])
 
-  AS_CASE([$host], [*android*], [qt_lib_suffix=_$ANDROID_ARCH])
-
   AC_ARG_WITH([qt-incdir],[AS_HELP_STRING([--with-qt-incdir=INC_DIR],[specify qt include path (overridden by pkgconfig)])], [qt_include_path=$withval], [])
   AC_ARG_WITH([qt-libdir],[AS_HELP_STRING([--with-qt-libdir=LIB_DIR],[specify qt lib path (overridden by pkgconfig)])], [qt_lib_path=$withval], [])
   AC_ARG_WITH([qt-plugindir],[AS_HELP_STRING([--with-qt-plugindir=PLUGIN_DIR],[specify qt plugin path (overridden by pkgconfig)])], [qt_plugin_path=$withval], [])
@@ -80,19 +78,10 @@ AC_DEFUN([BITCOIN_QT_INIT],[
 
   AC_ARG_WITH([qtdbus],
     [AS_HELP_STRING([--with-qtdbus],
-    [enable DBus support (default is yes if qt is enabled and QtDBus is found, except on Android)])],
+    [enable DBus support (default is yes if qt is enabled and QtDBus is found)])],
     [use_dbus=$withval],
     [use_dbus=auto])
 
-  dnl Android doesn't support D-Bus and certainly doesn't use it for notifications
-  case $host in
-    *android*)
-      if test "$use_dbus" != "yes"; then
-        use_dbus=no
-      fi
-    ;;
-  esac
-
   AC_SUBST(QT_TRANSLATION_DIR,$qt_translation_path)
 ])
 
@@ -132,16 +121,11 @@ AC_DEFUN([BITCOIN_QT_CONFIGURE],[
       if test -d "$qt_plugin_path/accessible"; then
         QT_LIBS="$QT_LIBS -L$qt_plugin_path/accessible"
       fi
-      if test -d "$qt_plugin_path/platforms/android"; then
-        QT_LIBS="$QT_LIBS -L$qt_plugin_path/platforms/android -lqtfreetype -lEGL"
-      fi
     fi
 
     AC_DEFINE([QT_STATICPLUGIN], [1], [Define this symbol if qt plugins are static])
-    if test "$TARGET_OS" != "android"; then
-      _BITCOIN_QT_CHECK_STATIC_PLUGIN([QMinimalIntegrationPlugin], [-lqminimal])
-      AC_DEFINE([QT_QPA_PLATFORM_MINIMAL], [1], [Define this symbol if the minimal qt platform exists])
-    fi
+    _BITCOIN_QT_CHECK_STATIC_PLUGIN([QMinimalIntegrationPlugin], [-lqminimal])
+    AC_DEFINE([QT_QPA_PLATFORM_MINIMAL], [1], [Define this symbol if the minimal qt platform exists])
     if test "$TARGET_OS" = "windows"; then
       dnl Linking against wtsapi32 is required. See #17749 and
       dnl https://bugreports.qt.io/browse/QTBUG-27097.
@@ -160,9 +144,6 @@ AC_DEFUN([BITCOIN_QT_CONFIGURE],[
       _BITCOIN_QT_CHECK_STATIC_PLUGIN([QCocoaIntegrationPlugin], [-lqcocoa])
       _BITCOIN_QT_CHECK_STATIC_PLUGIN([QMacStylePlugin], [-lqmacstyle])
       AC_DEFINE([QT_QPA_PLATFORM_COCOA], [1], [Define this symbol if the qt platform is cocoa])
-    elif test "$TARGET_OS" = "android"; then
-      QT_LIBS="-Wl,--export-dynamic,--undefined=JNI_OnLoad -lplugins_platforms_qtforandroid${qt_lib_suffix} -ljnigraphics -landroid -lqtfreetype${qt_lib_suffix} $QT_LIBS"
-      AC_DEFINE([QT_QPA_PLATFORM_ANDROID], [1], [Define this symbol if the qt platform is android])
     fi
   fi
   CPPFLAGS=$TEMP_CPPFLAGS
@@ -357,9 +338,6 @@ AC_DEFUN([_BITCOIN_QT_CHECK_STATIC_LIBS], [
     PKG_CHECK_MODULES([QT_SERVICE], [${qt_lib_prefix}ServiceSupport${qt_lib_suffix}], [QT_LIBS="$QT_SERVICE_LIBS $QT_LIBS"])
   elif test "$TARGET_OS" = "windows"; then
     PKG_CHECK_MODULES([QT_WINDOWSUIAUTOMATION], [${qt_lib_prefix}WindowsUIAutomationSupport${qt_lib_suffix}], [QT_LIBS="$QT_WINDOWSUIAUTOMATION_LIBS $QT_LIBS"])
-  elif test "$TARGET_OS" = "android"; then
-    PKG_CHECK_MODULES([QT_EGL], [${qt_lib_prefix}EglSupport${qt_lib_suffix}], [QT_LIBS="$QT_EGL_LIBS $QT_LIBS"])
-    PKG_CHECK_MODULES([QT_SERVICE], [${qt_lib_prefix}ServiceSupport${qt_lib_suffix}], [QT_LIBS="$QT_SERVICE_LIBS $QT_LIBS"])
   fi
 ])