[scudo] Disable the GetRssFromBuffer scudo test on PPC

The GetRssFromBuffer scudo test case fails intermittently on Power, so this test
is disabled on the platform because of this.

(cherry picked from commit 0e3ef5f)

Author: amy-kwan

compiler-rt/lib/scudo/standalone/tests/common_test.cpp

@@ -69,7 +69,9 @@ TEST(ScudoCommonTest, Zeros) {
   unmap(P, Size, 0, &Data);
 }
 
-#if SCUDO_LINUX
+#if SCUDO_LINUX && !defined(__powerpc__)
+// This test fails intermediately on PPC, which is why this test is disabled
+// for now on this platform.
 TEST(ScudoCommonTest, GetRssFromBuffer) {
   constexpr int64_t AllocSize = 10000000;
   constexpr int64_t Error = 3000000;