Update Android port

Update Android port

* INSTALL.android: Update.
* build-aux/ndk-build-helper-1.mk: Fix typo.
* configure.ac: Enable --with-json on Android.
* cross/ndk-build/ndk-build-shared-library.mk:
(NDK_CFLAGS_$(LOCAL_MODULE)):
(LOCAL_MODULE_FILENAME):
* cross/ndk-build/ndk-build-static-library.mk:
(ALL_OBJECT_FILES$(LOCAL_MODULE)):
(LOCAL_MODULE_FILENAME): Recursively resolve dependencies.
* cross/ndk-build/ndk-resolve.mk: New function.

* doc/emacs/android.texi (Android Startup): Document how Emacs
is dumped during initial startup.

* java/Makefile.in (filename): Fix build with multiple shared
libraries.
* java/README: Improve commentary.
* java/org/gnu/emacs/EmacsApplication.java (onCreate): Look and
set dump file.
* java/org/gnu/emacs/EmacsNative.java (EmacsNative): New
function getFingerprint.
* java/org/gnu/emacs/EmacsPreferencesActivity.java (onCreate):
Add option to erase the dump file.
* java/org/gnu/emacs/EmacsService.java (browseUrl): New
function.
* java/org/gnu/emacs/EmacsThread.java (run): Specify dump file
if found.
* lisp/loadup.el: Always dump during loadup on Android.

* lisp/net/browse-url.el (browse-url--browser-defcustom-type):
(browse-url-default-browser):
(browse-url-default-android-browser): New browse url type.

* m4/ndk-build.m4 (ndk_package_map): Map jansson to libjansson.
* src/android.c (struct android_emacs_service): New method
`browse_url'.
(getFingerprint): New function.
(android_init_emacs_service): Initialize new method.
(android_browse_url): New function.

* src/android.h: Update prototypes.

* src/androidselect.c (Fandroid_browse_url): New function.
(syms_of_androidselect): Define it.

* src/emacs.c (load_pdump): Don't look in fancy places on
Android.
* src/pdumper.c (Fdump_emacs_portable): Allow dumping while
interactive on Android.
(syms_of_pdumper): New variable `pdumper-fingerprint'.

* src/sfntfont-android.c (sfntfont_android_composite_bitmap):
Fix unused variables.