Order the type traits according to the standard's listing of unary type
traits where possible. For the rest, group them and add some
documentation regarding their origins.

No functionality change intended.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@130639 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed