[build] Fix build when using nested CMake

(FetchContent, ExternalProject_Add)

github: closes #102

CMakeLists.txt

@@ -2,7 +2,7 @@ project(lighttpd C)
 
 cmake_minimum_required(VERSION 2.8.2 FATAL_ERROR)
 
-set(CMAKE_MODULE_PATH ${CMAKE_SOURCE_DIR}/scripts/cmake)
+set(CMAKE_MODULE_PATH ${CMAKE_CURRENT_SOURCE_DIR}/scripts/cmake)
 
 include(CTest)
 

scripts/cmake/LighttpdMacros.cmake

@@ -25,9 +25,9 @@ endmacro(ADD_AND_INSTALL_LIBRARY)
 macro(LEMON_PARSER SRCFILE)
 	get_filename_component(SRCBASE ${SRCFILE} NAME_WE)
 	add_custom_command(OUTPUT ${CMAKE_CURRENT_BINARY_DIR}/${SRCBASE}.c ${CMAKE_CURRENT_BINARY_DIR}/${SRCBASE}.h
-		COMMAND ${CMAKE_BINARY_DIR}/build/lemon
-		ARGS -q ${CMAKE_CURRENT_SOURCE_DIR}/${SRCFILE} ${CMAKE_SOURCE_DIR}/src/lempar.c
-		DEPENDS ${CMAKE_BINARY_DIR}/build/lemon ${CMAKE_CURRENT_SOURCE_DIR}/${SRCFILE} ${CMAKE_SOURCE_DIR}/src/lempar.c
+		COMMAND ${CMAKE_CURRENT_BINARY_DIR}/lemon
+		ARGS -q ${CMAKE_CURRENT_SOURCE_DIR}/${SRCFILE} ${CMAKE_CURRENT_SOURCE_DIR}/lempar.c
+		DEPENDS ${CMAKE_CURRENT_BINARY_DIR}/lemon ${CMAKE_CURRENT_SOURCE_DIR}/${SRCFILE} ${CMAKE_CURRENT_SOURCE_DIR}/lempar.c
 		COMMENT "Generating ${SRCBASE}.c from ${SRCFILE}"
 	)
 endmacro(LEMON_PARSER)