Remove some 'const' specifiers that do nothing but prevent moving the argument.

Found by clang-tidy's misc-move-const-arg. While there drop some
obsolete c_str() calls.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@271181 91177308-0d34-0410-b5e6-96231b3b80d8
7 files changed