[fuzzer] Initialize PcDescr buffer before calling __sanitizer_symbolize_pc

__sanitizer_symbolize_pc is not instrumented so msan assumes that PcDescr
was not initialized.

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk/lib/fuzzer@318488 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/FuzzerUtil.cpp b/FuzzerUtil.cpp
index 65f0e17..96b37d3 100644
--- a/FuzzerUtil.cpp
+++ b/FuzzerUtil.cpp
@@ -181,7 +181,7 @@
 
 std::string DescribePC(const char *SymbolizedFMT, uintptr_t PC) {
   if (!EF->__sanitizer_symbolize_pc) return "<can not symbolize>";
-  char PcDescr[1024];
+  char PcDescr[1024] = {};
   EF->__sanitizer_symbolize_pc(reinterpret_cast<void*>(PC),
                                SymbolizedFMT, PcDescr, sizeof(PcDescr));
   PcDescr[sizeof(PcDescr) - 1] = 0;  // Just in case.