Dependencies for lua-2.3.1

Use the system-wide Lua instead of the bundled copy.

Compile Lua with -DLUA_USE_APICHECK.

Compile Lua with -DLUA_32BITS

Allow optimizations which make Lua's garbage collection potentially unsafe; enabling this should be safe if there are no callbacks into Haskell during Lua garbage collection cycles. The flag should be *disabled* if Lua objects can have Haskell finalizers, i.e., __gc metamethods that call Haskell function.

Add all symbols to dynamic symbol table; disabling this will make it possible to create fully static binaries, but renders loading of dynamic C libraries impossible.

Use pkg-config to discover library and include paths. Setting this flag implies `system-lua`.

Avoids constructs that would prevent cross-compilation. The Lua version constants may become inaccurate when this flag is enabled.