RFR (XS): 8043210: Add _BIG_ENDIAN define on linux/sparc

[Mikael Vidstedt]

Please review the following change, destined for jdk7u-dev. The zip 
implementation in unpack200 depends on _BIG_ENDIAN being defined on big 
endian platforms, and the define is missing on the linux/sparc platform(s).

Note that in the new build system (jdk8+) the relevant logic was 
rewritten, so the problem does not exists there.

Bug: https://bugs.openjdk.java.net/browse/JDK-8043210
Webrev: http://cr.openjdk.java.net/~mikael/webrevs/8043210/webrev.00/webrev/

Thanks,
Mikael