And fix the double-[]. It was including the [] as part of
the project name somehow, resulting in PACKAGE_TARNAME "-llvm-"
and a strange docdir default:

./configure --help | grep docdir
  --docdir=DIR           documentation root [DATAROOTDIR/doc/-llvm-]



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@146849 91177308-0d34-0410-b5e6-96231b3b80d8