Fix 32-bit test-suite build on AIX
For 32-bit programs on AIX, the default maximum size for the programs data heap could be too small for some of the test-suite cases. This patch sets the maximum heap size to 0x80000000 such that cases requiring larger heap size can properly load at runtime.
Reviewed By: daltenty
Differential Revision: https://reviews.llvm.org/D99752