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.
revert #652

reverting broad cosmetic/style change because:
- increases merge-conflicts
- increases overhead of merging upstream Vim patches
- reasons for change are ambiguous, so default to no change
Replace 'alloc' with 'xmalloc' in some files.

Files changed: charset.c, buffer.c, diff.c, edit.c,
ex_cmds.c, ex_cmds2.c and ex_docmd.c.

The remaining alloc's in these files require more careful attention to
remove.
Generate a lua module to help pass build-related settings.

This allows us to avoid hard-coding paths and using environment
variables to communicate key information to unit tests, which fits
with the overall goal of making sure that folks driving CMake directly
can continue to do out-of-tree builds.