llvm-mc: Default -triple to LLVM_HOSTTRIPLE.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@76260 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/tools/llvm-mc/llvm-mc.cpp b/tools/llvm-mc/llvm-mc.cpp
index c7f3996..6855a83 100644
--- a/tools/llvm-mc/llvm-mc.cpp
+++ b/tools/llvm-mc/llvm-mc.cpp
@@ -41,7 +41,7 @@
 static cl::opt<std::string>
 Triple("triple", cl::desc("Target triple to assemble for,"
                           "see -version for available targets"),
-       cl::init(""));
+       cl::init(LLVM_HOSTTRIPLE));
 
 enum ActionType {
   AC_AsLex,