Same as lua.eclass and python-r1, this is a Lua version of python-single-r1. Setting LUA_SINGLE_TARGETS allows one to choose the (slotted) Lua implementation to build your ebuild against, optionally including both single- and multi-implementation Lua packages as dependencies.
Tested using modified ebuilds of the following packages: - dev-lua/lgi - the multi-impl package I previously used to test lua.eclass, rebuilt this time to make sure said eclass still works properly after having moved some variables and functions to lua-utils.eclass (it does); - x11-wm/awesome - single-implementation, unconditionally depends on both dev-lang/lua itself and dev-lua/lgi (as well as some other dev-lua packages used by the test suite, which however I ignored). Links fine against whichever Lua version is selected by LUA_SINGLE_TARGET, requiring correct LUA_TARGETS to be enabled for dev-lua/lgi in either case; - media-gfx/darktable - conditional dependency on dev-lang/lua controlled by USE=lua. Also builds fine, although with it only supporting lua-5.3+ there wasn't much I could do in terms of version switching beyond confirming that LUA_REQUIRED_USE correctly specifies that exactly one single target must be specified.
