Fix libc++ pretty printer test for Python 3 after D67238 (take 2)
Fix libc++ pretty printer test for Python 3 after D67238 (take 2)

In both Python 2 and Python 3, gdb.Value.string returns a 'str'. We just
need to delete a `encode("utf-8")` which would return a 'bytes' in
Python 3.

git-svn-id: 756ef344af921d95d562d9e9f9389127a89a6314@373570 91177308-0d34-0410-b5e6-96231b3b80d8

llvm-mirror/libcxx,llvm-mirror/libcxx,llvm-mirror/libcxx,llvm-mirror/libcxx,llvm-mirror/libcxx