Change a build-attribute REQUIRES check to use supported not requested.

Previously it would print both the targets compiled-in and the
target requested on the commandline, but we really only care
about what's compiled-in.

BUG=none
R=stichnot@chromium.org

Review URL: https://codereview.chromium.org/1132883003
diff --git a/src/IceCompiler.cpp b/src/IceCompiler.cpp
index 7c8b791..0ef2ffd 100644
--- a/src/IceCompiler.cpp
+++ b/src/IceCompiler.cpp
@@ -47,11 +47,8 @@
 // Validates values of build attributes. Prints them to Stream if
 // Stream is non-null.
 void ValidateAndGenerateBuildAttributes(const ClFlags &Flags, Ostream *Stream) {
+  // List the supported targets.
   if (Stream) {
-    // List the requested target.
-    *Stream << Flags.getTargetArch() << "\n";
-
-// List the supported targets.
 #define SUBZERO_TARGET(TARGET) *Stream << "target_" #TARGET << "\n";
 #include "llvm/Config/SZTargets.def"
   }