Patch from Andrew Kaylor that fixes Linux default host triple values.

git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@165728 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/source/Host/common/Host.cpp b/source/Host/common/Host.cpp
index 4ed06c0..e586668 100644
--- a/source/Host/common/Host.cpp
+++ b/source/Host/common/Host.cpp
@@ -332,6 +332,11 @@
         g_host_arch_32.Clear();
         g_host_arch_64.Clear();
 
+        // If the OS is Linux, "unknown" in the vendor slot isn't what we want
+        // for the default triple.  It's probably an artifact of config.guess.
+        if (triple.getOS() == llvm::Triple::Linux && triple.getVendor() == llvm::Triple::UnknownVendor)
+            triple.setVendorName("");
+
         switch (triple.getArch())
         {
         default: