RFR (XS) 8239007: java/math/BigInteger/largeMemory/ tests should be disabled on 32-bit platforms

[Aleksey Shipilev]

Test bug:
  https://bugs.openjdk.java.net/browse/JDK-8239007

Fix:
  https://cr.openjdk.java.net/~shade/8239007/webrev.01/

Follows the precedent of:
  https://hg.openjdk.java.net/jdk/jdk/rev/848859723503

Testing: affected tests on Linux {x86_64, x86_32}

-- 
Thanks,
-Aleksey