[asan] Fix-forward #133175 by restricting newly-added tests to Linux

This was failing on Mac
(https://green.lab.llvm.org/job/llvm.org/job/clang-stage1-RA/4107/ and
https://issues.chromium.org/issues/409995888). Since this is an
experimental feature, rather than play whack-a-mole with selectively
disabling failing platforms (previously done for Android), this patch
restricts it to Linux.

Author: thurstond

compiler-rt/test/asan/TestCases/use-after-poison-history-size-partial-granule.cpp

@@ -6,6 +6,7 @@
 // RUN: %clangxx_asan -O0 %s -o %t && env ASAN_OPTIONS=poison_history_size=1000 not %run %t    2>&1 | FileCheck %s
 
 // TODO
+// REQUIRES: linux
 // UNSUPPORTED: android
 
 #include <stdio.h>

compiler-rt/test/asan/TestCases/use-after-poison-history-size.cpp

@@ -17,6 +17,7 @@
 // RUN: %clangxx_asan -O0 %s -o %t && env ASAN_OPTIONS=poison_history_size=1    not %run %t       2>&1 | FileCheck %s --check-prefixes=CHECK-ACDE,CHECK-BDE,CHECK-E
 
 // TODO
+// REQUIRES: linux
 // UNSUPPORTED: android
 
 #include <stdio.h>