Author: Nathan Phillip Brink <ohnobinki@ohnopublishing.net>
Purpose: To enable supertux to link against system-installed libsquirrel (as installed with pkg-config files by dev-lang/squirrel), tinygettext (whose API will someday change to be more ABI-friendly), and findlocale (which grumbel claims is pointless to externalize). This patch is not upstreamable because 1. upstream squirrel doesn't support system-installed squirrel at all and 2. tinygettext's API is C++ atm and will change.

diff -r e2cf0ccf00c7 CMakeLists.txt
--- a/CMakeLists.txt	Thu May 13 11:06:57 2010 -0400
+++ b/CMakeLists.txt	Fri May 14 02:20:14 2010 -0400
@@ -102,6 +102,21 @@
   SET(HAVE_LIBCURL TRUE)
 ENDIF(CURL_FOUND)
 
+INCLUDE(FindPkgConfig)
+pkg_check_modules(TINYGETTEXT tinygettext>=0.1)
+IF(TINYGETTEXT_FOUND)
+	SET(TINYGETTEXT_SOURCES_CXX "")
+	ADD_DEFINITIONS(${TINYGETTEXT_CFLAGS})
+ELSE(TINYGETTEXT_FOUND)
+	include_directories (${CMAKE_CURRENT_SOURCE_DIR}/external/tinygettext/)
+	FILE(GLOB TINYGETTEXT_SOURCES_CXX RELATIVE ${CMAKE_CURRENT_SOURCE_DIR} external/tinygettext/tinygettext/*.cpp)
+	SET_SOURCE_FILES_PROPERTIES(${TINYGETTEXT_SOURCES_CXX} PROPERTIES COMPILE_DEFINITIONS HAVE_SDL)
+ENDIF(TINYGETTEXT_FOUND)
+
+INCLUDE(FindPkgConfig)
+pkg_check_modules(FINDLOCALE REQUIRED findlocale>=0.47)
+ADD_DEFINITIONS(${FINDLOCALE_CFLAGS})
+
 #FIND_PACKAGE(ICONV REQUIRED)
 #INCLUDE_DIRECTORIES(${ICONV_INCLUDE_DIR})
 #LINK_LIBRARIES(${ICONV_LIBRARY})
@@ -149,31 +164,41 @@
 
 ## Also execute instructions in src/squirrel/CMakeLists.txt
 
-ADD_SUBDIRECTORY(external/squirrel)
+INCLUDE(FindPkgConfig)
 
-## Add squirrel lib dir to search path
+## check for external squirrel. To meet grumbel's requirements, must
+## default to internal squirrel.
+OPTION(EXTERNAL_LIBSQUIRREL "Build against external libsquirel libraries" OFF)
 
-LINK_DIRECTORIES(external/squirrel)
+IF(EXTERNAL_LIBSQUIRREL)
+  pkg_check_modules(LIBSQUIRREL REQUIRED libsquirrel>=2.2.4 libsqstdlib>=2.2.4)
+
+  ## libs are handled much further on
+  ADD_DEFINITIONS(${LIBSQUIRREL_CFLAGS})
+ELSE(EXTERNAL_LIBSQUIRREL)
+  ADD_SUBDIRECTORY(external/squirrel)
+
+  ## Add squirrel lib dir to search paths
+
+  LINK_DIRECTORIES(external/squirrel)
+
+  include_directories (${CMAKE_CURRENT_SOURCE_DIR}/external/squirrel/include/)
+  SET(LIBSQUIRREL_LIBRARIES squirrel)
+ENDIF(EXTERNAL_LIBSQUIRREL)
 
 ## Some additional include paths
 
 include_directories (${CMAKE_BINARY_DIR}/)
 include_directories (${CMAKE_CURRENT_SOURCE_DIR}/src/)
-include_directories (${CMAKE_CURRENT_SOURCE_DIR}/external/squirrel/include/)
-include_directories (${CMAKE_CURRENT_SOURCE_DIR}/external/tinygettext/)
-include_directories (${CMAKE_CURRENT_SOURCE_DIR}/external/findlocale/)
 include_directories (${CMAKE_CURRENT_SOURCE_DIR}/external/obstack/)
 include_directories (${CMAKE_CURRENT_SOURCE_DIR}/external/binreloc/)
 
 ## Build list of sources for supertux binary
 
-FILE(GLOB SUPERTUX_SOURCES_C RELATIVE ${CMAKE_CURRENT_SOURCE_DIR} external/obstack/*.c external/findlocale/findlocale.c)
+FILE(GLOB SUPERTUX_SOURCES_C RELATIVE ${CMAKE_CURRENT_SOURCE_DIR} external/obstack/*.c)
 
 FILE(GLOB SUPERTUX_SOURCES_CXX RELATIVE ${CMAKE_CURRENT_SOURCE_DIR} src/main.cpp src/*/*.cpp src/supertux/menu/*.cpp src/video/sdl/*.cpp)
 
-FILE(GLOB TINYGETTEXT_SOURCES_CXX RELATIVE ${CMAKE_CURRENT_SOURCE_DIR} external/tinygettext/tinygettext/*.cpp)
-SET_SOURCE_FILES_PROPERTIES(${TINYGETTEXT_SOURCES_CXX} PROPERTIES COMPILE_DEFINITIONS HAVE_SDL)
-
 IF(HAVE_OPENGL)
   FILE(GLOB SUPERTUX_OPENGL_SOURCES RELATIVE ${CMAKE_CURRENT_SOURCE_DIR} src/video/gl/*.cpp)
   SET(SUPERTUX_SOURCES_CXX ${SUPERTUX_SOURCES_CXX} ${SUPERTUX_OPENGL_SOURCES})
@@ -333,12 +358,13 @@
 
 ## Link supertux binary with squirrel and other libraries
 
-TARGET_LINK_LIBRARIES(supertux2 squirrel)
+TARGET_LINK_LIBRARIES(supertux2 ${LIBSQUIRREL_LIBRARIES})
 TARGET_LINK_LIBRARIES(supertux2 ${SDL_LIBRARY})
 TARGET_LINK_LIBRARIES(supertux2 ${SDLIMAGE_LIBRARY})
 TARGET_LINK_LIBRARIES(supertux2 ${OPENAL_LIBRARY})
 TARGET_LINK_LIBRARIES(supertux2 ${OGGVORBIS_LIBRARIES})
 TARGET_LINK_LIBRARIES(supertux2 ${PHYSFS_LIBRARY})
+TARGET_LINK_LIBRARIES(supertux2 ${FINDLOCALE_LDFLAGS})
 IF(HAVE_OPENGL)
     TARGET_LINK_LIBRARIES(supertux2 ${OPENGL_LIBRARY})
     TARGET_LINK_LIBRARIES(supertux2 ${GLEW_LIBRARY})
@@ -346,6 +372,9 @@
 IF(HAVE_LIBCURL)
   TARGET_LINK_LIBRARIES(supertux2 ${CURL_LIBRARY})
 ENDIF(HAVE_LIBCURL)
+IF(TINYGETTEXT_FOUND)
+    TARGET_LINK_LIBRARIES(supertux2 ${TINYGETTEXT_LDFLAGS})
+ENDIF(TINYGETTEXT_FOUND)
 
 ## Install stuff