Please backport dh-lua 19 (universe) from trusty

Please backport dh-lua 19 (universe) from trusty to precise.

Reason for the backport:
========================
Precise's dh-lua 11 doesn't support the LUA_SOURCES_MANGLER feature. This feature is used if Lua sources are in a subdirectory (e.g. `src/`) which should not be contained in the package. On Precise, this caused a Lua file to be installed into /usr/share/lua5.1/src instead of /usr/share/5.1.

Testing:
========

Built into ppa:fwalch/dh-lua using `backportpackage -u ppa:fwalch/dh-lua -s trusty -d precise dh-lua`.

* precise:
[x] Package builds without modification
[x] dh-lua installs cleanly and runs

Reverse dependencies:
=====================
Built into ppa:fwalch/dh-lua using `backportpackage -u ppa:fwalch/dh-lua -s precise -d precise lua-lgi`.

dh-lua
------
* lua-lgi
  [x] precise (Reverse-Build-Depends)