[test] Mark RISC-V pass-struct-by-value tests to avoid flaky status changes.

Bug: https://github.com/dart-lang/sdk/issues/48645
Change-Id: I3729c7df81ad2089224bf886a8c5345cc857f026
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/324764
Commit-Queue: Ryan Macnak <rmacnak@google.com>
Reviewed-by: Daco Harkes <dacoharkes@google.com>
diff --git a/tests/ffi/ffi.status b/tests/ffi/ffi.status
index 188dfc9..d178dfb 100644
--- a/tests/ffi/ffi.status
+++ b/tests/ffi/ffi.status
@@ -70,6 +70,9 @@
 vmspecific_regress_37780_test: SkipByDesign # Symbols are not exposed on purpose and are not linked in Windows Precompiled. dartbug.com/40579
 vmspecific_regress_51794_test: SkipByDesign # Symbols are not exposed on purpose and are not linked in Windows Precompiled. dartbug.com/40579
 
+[ $arch == riscv32 || $arch == riscv64 ]
+*structs_by_value*: Skip # https://dartbug.com/48645
+
 # These tests trigger and catch an abort (intentionally) and terminate the VM.
 # They're incompatible with ASAN because not all memory is freed when aborting and
 # with AppJit because the abort the VM before it can generate a snapshot.