Fix complete badness in bugpoint's IsARMArchitecture() function.

The revision history for this function is interesting, with multiple layers of
wrongness being introduced one at a time.

This fixes a weird issue where bugpoint -run-llc would suddenly exit 13 half way
through isolating a miscompilation.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@103721 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/tools/bugpoint/ToolRunner.cpp b/tools/bugpoint/ToolRunner.cpp
index 1ff44c7..4baafd1 100644
--- a/tools/bugpoint/ToolRunner.cpp
+++ b/tools/bugpoint/ToolRunner.cpp
@@ -620,10 +620,9 @@
 static bool IsARMArchitecture(std::vector<std::string> Args) {
   for (std::vector<std::string>::const_iterator
          I = Args.begin(), E = Args.end(); I != E; ++I) {
-    StringRef S(*I);
-    if (!S.equals_lower("-arch")) {
+    if (StringRef(*I).equals_lower("-arch")) {
       ++I;
-      if (I != E && !S.substr(0, strlen("arm")).equals_lower("arm"))
+      if (I != E && StringRef(*I).substr(0, strlen("arm")).equals_lower("arm"))
         return true;
     }
   }