Disable BitStructs::NestedFieldAssignment.

Test fails after:
https://android-review.googlesource.com/c/platform/build/soong/+/1209543

Bug: 148125232
Test: bit_struct_test
Change-Id: Ia098ac655c1e9b1232628e6988957a51a92f7fd9
diff --git a/libartbase/base/bit_struct_test.cc b/libartbase/base/bit_struct_test.cc
index a2389eb..1874a4d 100644
--- a/libartbase/base/bit_struct_test.cc
+++ b/libartbase/base/bit_struct_test.cc
@@ -290,7 +290,7 @@
   BitStructUint</*lsb=*/0, /*width=*/64> alias_all;
 BITSTRUCT_DEFINE_END(NestedStruct);
 
-TEST(BitStructs, NestedFieldAssignment) {
+TEST(BitStructs, DISABLED_NestedFieldAssignment) {
   MixedSizeBitStruct mixed_all_1s{};
   mixed_all_1s.alias_all = 0xFFFFFFFFu;