lua 5.2.3_1: Add -ldl to pkg-config --libs lua
lua 5.2.3_1: Add -ldl to pkg-config --libs lua

Fix the error:
/gsc/btl/linuxbrew/lib/liblua.a(loadlib.o): In function `ll_loadfunc':
loadlib.c:(.text+0x653): undefined reference to `dlopen'

Closes Homebrew/linuxbrew#194

forevergenin/homebrew-core,rwhogg/homebrew-core,LinuxbrewTestBot/homebrew-core,forevergenin/homebrew-core,maxim-belkin/homebrew-core,rwhogg/homebrew-core,Linuxbrew/homebrew-core,LinuxbrewTestBot/homebrew-core,Linuxbrew/homebrew-core,maxim-belkin/homebrew-core