Fix build and running on Android 2.2

Fix build and running on Android 2.2

* INSTALL.android: Document that Android 2.2 is now supported,
with caveats.
* configure.ac (ANDROID_MIN_SDK, ANDROID_SDK_18_OR_EARLIER)
(SYSTEM_TYPE, ANDROID_STUBIFY, SIZEOF_LONG): Correctly detect
things missing on Android 2.2.
* java/Makefile.in (ANDROID_JAR, JARSIGNER_FLAGS):
* java/debug.sh (jdb, gdbserver, line):
* java/org/gnu/emacs/EmacsApplication.java (findDumpFile):
* java/org/gnu/emacs/EmacsService.java (onCreate):
* java/org/gnu/emacs/EmacsThread.java (EmacsThread, run): Run
parameter initialization on main thread.
* src/android-asset.h (struct android_asset_manager)
(struct android_asset, AAssetManager_fromJava, AAssetManager_open)
(AAsset_close, android_asset_create_stream)
(android_asset_read_internal, AAsset_openFileDescriptor)
(AAsset_getLength, AAsset_getBuffer, AAsset_read): New file.
* src/android.c (android_user_full_name, android_hack_asset_fd)
(android_check_compressed_file): Implement for Android 2.2.
* src/process.c (Fprocess_send_eof): Don't call tcdrain if
unavailable.
* src/sfntfont-android.c (system_font_directories): Fix compiler
warning.
* src/sfntfont.c (sfntfont_read_cmap): Correctly test rc of
emacs_open.
* src/textconv.c (handle_pending_conversion_events_1): Mark
buffer UNINIT.