[ADT] Make escaping fn conform to coding guidelines

As noted by Adrian on llvm-commits, PrintHTMLEscaped and PrintEscaped in
StringExtras did not conform to the LLVM coding guidelines. This commit
rectifies that.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@333669 91177308-0d34-0410-b5e6-96231b3b80d8
8 files changed