Revert svn r176894 and r177658.

Changing -ccc-install-dir to affect cc1's resource-dir setting broke our
internal LNT tests. After discussing the situation with Jim, we've decided to
pursue an alternate approach. We really want the resource-dir to be located
relative to clang, even when using -ccc-install-dir, but we're going to
add a fallback setting for the libc++ headers if they don't exist alongside
the compiler.

llvm-svn: 177815
diff --git a/clang/lib/Driver/Driver.cpp b/clang/lib/Driver/Driver.cpp
index 3167e03..689ecbc 100644
--- a/clang/lib/Driver/Driver.cpp
+++ b/clang/lib/Driver/Driver.cpp
@@ -59,6 +59,15 @@
 
   Name = llvm::sys::path::stem(ClangExecutable);
   Dir  = llvm::sys::path::parent_path(ClangExecutable);
+
+  // Compute the path to the resource directory.
+  StringRef ClangResourceDir(CLANG_RESOURCE_DIR);
+  SmallString<128> P(Dir);
+  if (ClangResourceDir != "")
+    llvm::sys::path::append(P, ClangResourceDir);
+  else
+    llvm::sys::path::append(P, "..", "lib", "clang", CLANG_VERSION_STRING);
+  ResourceDir = P.str();
 }
 
 Driver::~Driver() {
@@ -282,18 +291,8 @@
   if (Args->hasArg(options::OPT_nostdlib))
     UseStdLib = false;
 
-  // Compute the path to the resource directory. We used to do this in
-  // Driver::Driver(), but that's not right, as command line args (such as
-  // ccc-install-dir) can change 'Dir'.
-  StringRef ClangResourceDir(CLANG_RESOURCE_DIR);
-  SmallString<128> P(Dir);
   if (const Arg *A = Args->getLastArg(options::OPT_resource_dir))
-    P = A->getValue();
-  else if (!ClangResourceDir.empty())
-    llvm::sys::path::append(P, ClangResourceDir);
-  else
-    llvm::sys::path::append(P, "..", "lib", "clang", CLANG_VERSION_STRING);
-  ResourceDir = P.str();
+    ResourceDir = A->getValue();
 
   // Perform the default argument translations.
   DerivedArgList *TranslatedArgs = TranslateInputArgs(*Args);