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


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@297614 91177308-0d34-0410-b5e6-96231b3b80d8