feature test macro requirements (this example from readahead (2)): #define _GNU_SOURCE #define _FILE_OFFSET ... BITS 64 #include ssize_t readahead(int fd , off_t * offset , size_…feature test macro requirements (this example from readahead (2)): #define _GNU_SOURCE #define _FILE_OFFSET ... BITS 64 #include ssize_t readahead(int fd , off_t * offset , size_…