Disable two failing sandbox_linux_unittests on Android L & M.

Disable:
- ParameterRestrictions.ptrace_getregs_allowed
- ParameterRestrictions.ptrace_syscall_blocked

They have been introduced recently by:
https://chromium-review.googlesource.com/c/chromium/src/+/1487519

Unfortunately, they aren't working yet on Android version L and M.

Tbr: rsesek@chromium.org
Bug: 934930
Change-Id: I22a5034ad6638ca3be7c0231c7e25445bd9720ee
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1539849Reviewed-by: Arthur Sonzogni <arthursonzogni@chromium.org>
Commit-Queue: Arthur Sonzogni <arthursonzogni@chromium.org>
Cr-Commit-Position: refs/heads/master@{#644724}

sandbox/linux/seccomp-bpf-helpers/syscall_parameters_restrictions_unittests.cc

@@ -415,8 +415,10 @@ class PtraceTestHarness {
   DISALLOW_COPY_AND_ASSIGN(PtraceTestHarness);
 };
 
+// Fails on Android L and M.
+// See https://crbug.com/934930
 BPF_TEST_C(ParameterRestrictions,
-           ptrace_getregs_allowed,
+           DISABLED_ptrace_getregs_allowed,
            RestrictPtracePolicy) {
   auto tracer = [](pid_t pid) {
 #if defined(__arm__)
@@ -435,8 +437,10 @@ BPF_TEST_C(ParameterRestrictions,
   PtraceTestHarness(tracer, false).Run();
 }
 
+// Fails on Android L and M.
+// See https://crbug.com/934930
 BPF_TEST_C(ParameterRestrictions,
-           ptrace_syscall_blocked,
+           DISABLED_ptrace_syscall_blocked,
            RestrictPtracePolicy) {
   auto tracer = [](pid_t pid) {
     // The tracer is about to die. Make sure the tracee is not stopped so it