cmake: Build bcc-lua conditionally

src/lua/CMakeLists.txt

 include(cmake/FindLuaJIT.cmake)
-find_program(LUAJIT luajit)
 
-FILE(GLOB_RECURSE SRC_LUA ${CMAKE_CURRENT_SOURCE_DIR}/bcc/*/*.lua)
+if (LUAJIT_LIBRARIES)
+	find_program(LUAJIT luajit)
+	FILE(GLOB_RECURSE SRC_LUA ${CMAKE_CURRENT_SOURCE_DIR}/bcc/*/*.lua)
 
-ADD_CUSTOM_COMMAND(
-	OUTPUT ${CMAKE_CURRENT_SOURCE_DIR}/src/bcc.lua
-	COMMAND ${LUAJIT} src/squish.lua
-	DEPENDS ${SRC_LUA} ${CMAKE_CURRENT_SOURCE_DIR}/squishy
-	WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}
-)
+	ADD_CUSTOM_COMMAND(
+		OUTPUT ${CMAKE_CURRENT_SOURCE_DIR}/src/bcc.lua
+		COMMAND ${LUAJIT} src/squish.lua
+		DEPENDS ${SRC_LUA} ${CMAKE_CURRENT_SOURCE_DIR}/squishy
+		WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}
+	)
 
-ADD_CUSTOM_COMMAND(
-	OUTPUT ${CMAKE_CURRENT_SOURCE_DIR}/src/bcc.o
-	COMMAND ${LUAJIT} -bg src/bcc.lua src/bcc.o
-	DEPENDS ${CMAKE_CURRENT_SOURCE_DIR}/src/bcc.lua
-	WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}
-)
+	ADD_CUSTOM_COMMAND(
+		OUTPUT ${CMAKE_CURRENT_SOURCE_DIR}/src/bcc.o
+		COMMAND ${LUAJIT} -bg src/bcc.lua src/bcc.o
+		DEPENDS ${CMAKE_CURRENT_SOURCE_DIR}/src/bcc.lua
+		WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}
+	)
 
-include_directories(${LUAJIT_INCLUDE_DIR})
-add_executable(bcc-lua src/main.c src/bcc.o)
-target_link_libraries(bcc-lua ${LUAJIT_LIBRARIES})
+	include_directories(${LUAJIT_INCLUDE_DIR})
+	add_executable(bcc-lua src/main.c src/bcc.o)
+	target_link_libraries(bcc-lua ${LUAJIT_LIBRARIES})
+endif()