removed as a duplicate header search path
The commit r126167 started passing the First index into RemoveDuplicates, but
forgot to update 0 to First in the loop that looks for the duplicate. This
resulted in a bug where an -iquoted search path was incorrectly removed if you
passed in the same path into -iquote and more than one time into -isystem.
rdar://23991350
Differential Revision: https://reviews.llvm.org/D27298
llvm-svn: 288491
Alex Lorenz