[libFuzzer] Properly check if we can use dumpbin.

The flag "/sumary" is necessary, otherwise it returns a non-zero value.

Differential Revision: https://reviews.llvm.org/D29371

llvm-svn: 293790

llvm/lib/Fuzzer/FuzzerUtilWindows.cpp

@@ -179,7 +179,7 @@ const void *SearchMemory(const void *Data, size_t DataLen, const void *Patt,
 }
 
 std::string DisassembleCmd(const std::string &FileName) {
-  if (ExecuteCommand("dumpbin > nul") == 0)
+  if (ExecuteCommand("dumpbin /summary > nul") == 0)
     return "dumpbin /disasm " + FileName;
   if (ExecuteCommand("llvm-objdump > nul") == 0)
     return "llvm-objdump -d " + FileName;