add Android support commit to m4/libtool.m4 on any project that uses it

refs #1548
set min platform to android-14/4.0/Ice Cream Sandwich

Its currently too much work for us to handle supporting older versions.
This relies on a lot of new APIs both in the SDK, like the Contacts
handling, and in the NDK, with things like missing pthread_atfork():

http://bugs.g10code.com/gnupg/issue1576

Update target to the latest while I'm at it.
bump version to 0.3 code 4
include all CPU-specific JNI build folders
more reliable integration of Android NDK build files into external/Makefile

Now the build target for SDK, NDK, and external/Makefile are all set from
AndroidManifest.xml.

refs #1630
make compile error whenever there is a security issue with formats

-Wformat -Werror=format-security
add Posix.symlink() for making symlinks with needing `ln -s`

We have no guarantee that `ln -s` will be included in all Android distros,
but since most provide `ln -s`, I think we can be resonably sure that the
libc everywhere will include symlink().

Its also really a pain to run shell commands in Java for simple things like
this.