[LSAN] Attempt to fix the ppc64 build by excluding unsupported test

Reviewed By: kstoimenov

Differential Revision: https://reviews.llvm.org/D142561

(cherry picked from commit 3348699)

Author: kstoimenov

compiler-rt/test/lsan/TestCases/Linux/leak_check_segv.cpp

@@ -1,5 +1,6 @@
 // Test that SIGSEGV during leak checking does not crash the process.
 // RUN: %clangxx_lsan -O1 %s -o %t && not %run %t 2>&1 | FileCheck %s
+// UNSUPPORTED: ppc
 #include <stdlib.h>
 #include <stdio.h>
 #include <sys/mman.h>