Cache effective-target llvm_binutils result.

2019-01-30  Andrew Stubbs  <ams@codesourcery.com>

	PR testsuite/88920

	gcc/testsuite/
	* lib/target-supports.exp: Cache result.

From-SVN: r268384

gcc/testsuite/ChangeLog

+2019-01-30  Andrew Stubbs  <ams@codesourcery.com>
+
+	PR testsuite/88920
+
+	* lib/target-supports.exp: Cache result.
+
 2019-01-30  Jakub Jelinek  <jakub@redhat.com>
 
 	PR c++/89105

gcc/testsuite/lib/target-supports.exp

@@ -9263,6 +9263,7 @@ foreach N {df} {
 
 # Return 1 if this target uses an LLVM assembler and/or linker
 proc check_effective_target_llvm_binutils { } {
-    return [expr { [istarget amdgcn*-*-*]
-		   || [check_effective_target_offload_gcn] } ]
+    return [check_cached_effective_target llvm_binutils {
+	      expr { [istarget amdgcn*-*-*]
+		     || [check_effective_target_offload_gcn] }}]
 }