Add JDK 8 ABI detection to ARM GNU/Linux shared library loading.

This change will enable libgdx to load ARM specific native library’s on ARM GNU/Linux systems.
JDK 8 introduced sun.arch.abi that tell which ABI of the ARM library to be loaded.
JDK 6/7 users have to be careful to deploy the right ABI of the libgdx natives that match their ARM system.

JDK 8 ARM systems will try to load:
lib*armgnueabi.so -> 32bit ARM GNU softfp EABI
lib*armgnueabihf.so -> 32bit ARM GNU hard float EABI
lib*armandroideabi.so -> 32bit Android EABI

JDK 6/7 ARM systems will try to load:
lib*arm.so -> 32bit ARM unknown ABI.

Signed-off-by: Xerxes Rånby <xerxes@zafena.se>