[llvm-dlltool] Map the "arm64" machine type

Differential Revision: https://reviews.llvm.org/D36365

llvm-svn: 310223
diff --git a/llvm/lib/ToolDrivers/llvm-dlltool/DlltoolDriver.cpp b/llvm/lib/ToolDrivers/llvm-dlltool/DlltoolDriver.cpp
index a7de793..c929c90 100644
--- a/llvm/lib/ToolDrivers/llvm-dlltool/DlltoolDriver.cpp
+++ b/llvm/lib/ToolDrivers/llvm-dlltool/DlltoolDriver.cpp
@@ -76,6 +76,7 @@
       .Case("i386", IMAGE_FILE_MACHINE_I386)
       .Case("i386:x86-64", IMAGE_FILE_MACHINE_AMD64)
       .Case("arm", IMAGE_FILE_MACHINE_ARMNT)
+      .Case("arm64", IMAGE_FILE_MACHINE_ARM64)
       .Default(IMAGE_FILE_MACHINE_UNKNOWN);
 }