Check if alarm() is in unistd.h for cmake

Author: brarcher

CMakeLists.txt

@@ -187,6 +187,7 @@ check_function_exists(strsignal HAVE_DECL_STRSIGNAL)
 check_function_exists(_getpid HAVE__GETPID)
 check_function_exists(_strdup HAVE__STRDUP)
 check_function_exists(alarm HAVE_DECL_ALARM)
+check_symbol_exists(alarm unistd.h HAVE_ALARM_SYMBOL)
 if (HAVE_WINDOWS_H)
   check_function_exists(InitOnceBeginInitialize HAVE_INIT_ONCE_BEGIN_INITIALIZE)
   check_function_exists(InitOnceComplete HAVE_INIT_ONCE_COMPLETE)