vim-patch:7.4.272

Problem:  Using just "$" does not cause an error message.
Solution: Check for empty environment variable name.
          (Christian Brabandt)

https://code.google.com/p/vim/source/detail?r=00228400629e28384f7f52556c3c119ba0d0a44d
Remove incorrect trailing backslash

If this backslash is here and USE_VALGRIND is defined, valgrind complains that "else" is not a command.