Add a missing header file


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@16099 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/tools/llvmc/CompilerDriver.cpp b/tools/llvmc/CompilerDriver.cpp
index 7dadf43..08559b8 100644
--- a/tools/llvmc/CompilerDriver.cpp
+++ b/tools/llvmc/CompilerDriver.cpp
@@ -16,6 +16,7 @@
 #include "ConfigLexer.h"
 #include "llvm/Module.h"
 #include "llvm/Bytecode/Reader.h"
+#include "llvm/System/Signals.h"
 #include "Support/FileUtilities.h"
 #include "Support/SetVector.h"
 #include "Support/StringExtras.h"