Review Request: 8006661: build-infra: Use LC_ALL=C instead of LANG=C in compare.sh

[Erik Joelsson]

Use LC_ALL=C instead of LANG=C because the latter does not change LC_MESSAGES, 
which is necessary if we are grepping for english words in the output from diff.

Contributed by ohrstrom

http://cr.openjdk.java.net/~erikj/8006661/webrev.root.01/

/Erik