Add support for musl-libc on ARM Linux.

Patch by Lei Zhang!

llvm-svn: 273726
diff --git a/llvm/unittests/ADT/TripleTest.cpp b/llvm/unittests/ADT/TripleTest.cpp
index c860222..294fcf5 100644
--- a/llvm/unittests/ADT/TripleTest.cpp
+++ b/llvm/unittests/ADT/TripleTest.cpp
@@ -141,6 +141,12 @@
   EXPECT_EQ(Triple::UnknownOS, T.getOS());
   EXPECT_EQ(Triple::EABI, T.getEnvironment());
 
+  T = Triple("arm-none-linux-musleabi");
+  EXPECT_EQ(Triple::arm, T.getArch());
+  EXPECT_EQ(Triple::UnknownVendor, T.getVendor());
+  EXPECT_EQ(Triple::Linux, T.getOS());
+  EXPECT_EQ(Triple::MuslEABI, T.getEnvironment());
+
   T = Triple("armv6hl-none-linux-gnueabi");
   EXPECT_EQ(Triple::arm, T.getArch());
   EXPECT_EQ(Triple::Linux, T.getOS());