XFailing test cases that fail on PowerPC

These test cases fail when the libcxx and libcxxabi runtimes are
built on Linux PowerPC. XFailing them until the issue is resolved.

Author: kamaub

libcxx/test/libcxx/containers/views/mdspan/layout_stride/assert.conversion.pass.cpp

@@ -10,6 +10,7 @@
 // UNSUPPORTED: c++03, c++11, c++14, c++17, c++20
 // UNSUPPORTED: libcpp-hardening-mode=none
 // XFAIL: availability-verbose_abort-missing
+// XFAIL: target=powerpc{{.*}}le-unknown-linux-gnu
 
 // <mdspan>
 

libcxx/test/std/experimental/simd/simd.class/simd_ctor_broadcast.pass.cpp

@@ -7,6 +7,7 @@
 //===----------------------------------------------------------------------===//
 
 // UNSUPPORTED: c++03, c++11, c++14
+// XFAIL: target=powerpc{{.*}}le-unknown-linux-gnu
 
 // <experimental/simd>
 //

libcxx/test/std/experimental/simd/simd.class/simd_ctor_conversion.pass.cpp

@@ -7,6 +7,7 @@
 //===----------------------------------------------------------------------===//
 
 // UNSUPPORTED: c++03, c++11, c++14
+// XFAIL: target=powerpc{{.*}}le-unknown-linux-gnu
 
 // <experimental/simd>
 //

libcxx/test/std/experimental/simd/simd.class/simd_ctor_generator.pass.cpp

@@ -7,6 +7,7 @@
 //===----------------------------------------------------------------------===//
 
 // UNSUPPORTED: c++03, c++11, c++14
+// XFAIL: target=powerpc{{.*}}le-unknown-linux-gnu
 
 // <experimental/simd>
 //

libcxx/test/std/experimental/simd/simd.class/simd_subscr.pass.cpp

@@ -7,6 +7,7 @@
 //===----------------------------------------------------------------------===//
 
 // UNSUPPORTED: c++03, c++11, c++14
+// XFAIL: target=powerpc{{.*}}le-unknown-linux-gnu
 
 // <experimental/simd>
 //

libcxx/test/std/experimental/simd/simd.reference/reference_assignment.pass.cpp

@@ -15,6 +15,7 @@
 //
 // [simd.reference]
 // template<class U> reference=(U&& x) && noexcept;
+// XFAIL: target=powerpc{{.*}}le-unknown-linux-gnu
 
 #include "../test_utils.h"
 #include <experimental/simd>

libcxx/test/std/experimental/simd/simd.reference/reference_value_type.pass.cpp

@@ -7,6 +7,7 @@
 //===----------------------------------------------------------------------===//
 
 // UNSUPPORTED: c++03, c++11, c++14
+// XFAIL: target=powerpc{{.*}}le-unknown-linux-gnu
 
 // <experimental/simd>
 //