Add -iframeworkwithsysroot compiler option

This commit adds support for a new -iframeworkwithsysroot compiler option which
allows the user to specify a framework path that can be prefixed with the
sysroot. This option is similar to the -iwithsysroot option that exists to
supplement -isystem.

rdar://21316352

Differential Revision: https://reviews.llvm.org/D30183

llvm-svn: 297614
diff --git a/clang/lib/Frontend/CompilerInvocation.cpp b/clang/lib/Frontend/CompilerInvocation.cpp
index 4d828f5..598af20 100644
--- a/clang/lib/Frontend/CompilerInvocation.cpp
+++ b/clang/lib/Frontend/CompilerInvocation.cpp
@@ -1507,6 +1507,9 @@
                  !A->getOption().matches(OPT_iwithsysroot));
   for (const Arg *A : Args.filtered(OPT_iframework))
     Opts.AddPath(A->getValue(), frontend::System, true, true);
+  for (const Arg *A : Args.filtered(OPT_iframeworkwithsysroot))
+    Opts.AddPath(A->getValue(), frontend::System, /*IsFramework=*/true,
+                 /*IgnoreSysRoot=*/false);
 
   // Add the paths for the various language specific isystem flags.
   for (const Arg *A : Args.filtered(OPT_c_isystem))