[test-suite][AIX] Enable profiling via hpmcount on AIX
Add --param=profile=hpmcount option to lit thus support profiling via hpmcount on AIX.
Each test will run under hpmcount and output data of hpmcount will be stored in Output directory. It's best run it after bindprocessor and use -j1.
Reviewed By: jsji
Differential Revision: https://reviews.llvm.org/D96002