Revert the default changing behavior part of r216662 until we
can change the backend to be the same default. Leave the
modified/new testcases with the exception of the default behavior
since it increases our testing footprint.

llvm-svn: 223976
diff --git a/clang/lib/Driver/Tools.cpp b/clang/lib/Driver/Tools.cpp
index 151d87b..67393ee 100644
--- a/clang/lib/Driver/Tools.cpp
+++ b/clang/lib/Driver/Tools.cpp
@@ -793,11 +793,10 @@
     case llvm::Triple::EABI:
       ABIName = "aapcs";
       break;
+    // This is also the case for netbsd.
+    case llvm::Triple::GNU:
     default:
-      if (Triple.getOS() == llvm::Triple::NetBSD)
-        ABIName = "apcs-gnu";
-      else
-        ABIName = "aapcs";
+      ABIName = "apcs-gnu";
       break;
     }
   }