[OpenMP][AIX] XFAIL capacity tests on AIX in 32-bit (#83014)

This patch XFAILs two capacity tests on AIX in 32-bit because running
out resource with `4 x omp_get_max_threads()` in 32-bit mode.

Author: xingxue-ibm

openmp/runtime/test/tasking/hidden_helper_task/capacity_mix_threads.cpp

@@ -1,4 +1,7 @@
 // RUN: %libomp-cxx-compile-and-run
+//
+// AIX runs out of resource in 32-bit with 4*omp_get_max_threads() threads.
+// XFAIL: aix && ppc
 
 #include <omp.h>
 

openmp/runtime/test/tasking/hidden_helper_task/capacity_nthreads.cpp

@@ -1,4 +1,7 @@
 // RUN: %libomp-cxx-compile-and-run
+//
+// AIX runs out of resource in 32-bit with 4*omp_get_max_threads() threads.
+// XFAIL: aix && ppc
 
 #include <omp.h>