RFR JDK-8141491: Unaligned memory access in Bits.c

[Alexander Smundak]

Please take a look at
http://cr.openjdk.java.net/~asmundak/8141491/jdk/webrev.00
that fixes the problem.

It utilizes the ability of some (GCC and Clang) to declare data
alignment explicitly.
I have verified it works on x86_64 Linux by running
jdk/test/java/nio/Buffer/Basic.java test

I need a sponsor.

Sasha