Enable libjpeg on Android

Enable libjpeg on Android

* INSTALL.android: Update documentation.
* build-aux/ndk-build-helper-1.mk: When building shared
libraries, do not link libemacs.so with dependent archive files.
* build-aux/ndk-build-helper-2.mk: Add whole archive
dependencies as well.

* configure.ac (HAVE_JPEG): Enable on Android.

* cross/ndk-build/ndk-build-shared-library.mk: Link the shared
object with archive file dependencies.
* cross/ndk-build/ndk-build-static-library.mk: Build all code
position-independently.
* cross/ndk-build/ndk-resolve.mk: Separately resolve a names of
archive and whole archive dependencies.

* src/Makefile.in (JPEG_CFLAGS): New variable.
(EMACS_CFLAGS): Add it.