Do this the right way

Modules/CMakeBackwardCompatibilityC.cmake

@@ -10,10 +10,12 @@ CHECK_TYPE_SIZE(float    CMAKE_SIZEOF_FLOAT)
 CHECK_TYPE_SIZE(double   CMAKE_SIZEOF_DOUBLE)
 
 INCLUDE (${CMAKE_ROOT}/Modules/CheckFunctionExists.cmake)
-CHECK_FUNCTION_EXISTS(gethostbyname CMAKE_HAVE_GETHOSTBYNAME)
 CHECK_FUNCTION_EXISTS(connect       CMAKE_HAVE_CONNECT)
 CHECK_FUNCTION_EXISTS(remove        CMAKE_HAVE_REMOVE)
-CHECK_FUNCTION_EXISTS(shmat         CMAKE_HAVE_SHMAT)
+
+INCLUDE (${CMAKE_ROOT}/Modules/CheckLibraryExists.cmake)
+CHECK_LIBRARY_EXISTS("nsl" "gethostbyname" "" CMAKE_HAVE_GETHOSTBYNAME)
+CHECK_LIBRARY_EXISTS("ipc" "shmat" "" CMAKE_HAVE_GETHOSTBYNAME)
 
 INCLUDE (${CMAKE_ROOT}/Modules/CheckIncludeFile.cmake)
 CHECK_INCLUDE_FILE("limits.h"       CMAKE_HAVE_LIMITS_H)