Building for Android by Android NDK.

Support for building OpenSSL for four 32-bit architectures supported by Android NDK.

Included:

- Changes to "config" and "Configure" scripts.

- New file: setenv-android.sh script, based on
  http://wiki.openssl.org/images/7/70/Setenv-android.sh script, mentioned at
  http://wiki.openssl.org/index.php/Android .

The compiler options in "Configure" script are based on:

- Existing options from previous versions of this script.

- Options that are supplied by Android NDK r10 for linux-x86_64, toolchains:
  arm-linux-androideabi-4.6, mipsel-linux-android-4.6, x86-4.6.
  As can be seen, NDK supplies quite different options are for different
  architectures.

- Considerations about footprint vs speed of the resulting code on mobile
  devices.