Add CheckLib.cmake

cmake/CheckLib.cmake

@@ -0,0 +1,36 @@
+include(FindPkgConfig OPTIONAL)
+
+macro(_internal_message msg)
+	message("${msg}")
+endmacro()
+
+macro(check_lib var lib)
+	set(_arg_list ${ARGN})
+
+	if(PKG_CONFIG_FOUND AND NOT ${var}_FOUND)
+		string(TOLOWER ${lib} lower_lib)
+		pkg_search_module(${var} QUIET ${lower_lib})
+	endif()
+
+	if(${var}_FOUND)
+		include_directories(${${var}_INCLUDE_DIRS})
+		# Make sure include directories for headers found using find_path below
+		# are re-added when reconfiguring
+		include_directories(${${var}_INCLUDE})
+		_internal_message("${lib} found")
+	else()
+		find_library(${var} ${lib})
+		if(_arg_list)
+			find_path(${var}_INCLUDE ${_arg_list})
+		else()
+			set(${var}_INCLUDE FALSE)
+		endif()
+		if(${var} AND ${var}_INCLUDE)
+			include_directories(${${var}_INCLUDE})
+			_internal_message("${lib} found")
+			set(${var}_FOUND 1 CACHE INTERNAL "")
+		else()
+			_internal_message("${lib} not found")
+		endif()
+	endif()
+endmacro()