libc: Add mkfifo() and pipe() to libc CSV file

libc/libc.csv

@@ -71,10 +71,12 @@
 "memcpy","string.h","","FAR void","FAR void *","FAR const void *","size_t"
 "memmove","string.h","","FAR void","FAR void *","FAR const void *","size_t"
 "memset","string.h","","FAR void","FAR void *","int c","size_t"
+"mkfifo","sys/stat.h","CONFIG_NFILE_DESCRIPTORS > 0","int","FAR const char*","mode_t"
 "mktime","time.h","","time_t","const struct tm *"
 "ntohl","arpa/inet.h","","uint32_t","uint32_t"
 "ntohs","arpa/inet.h","","uint16_t","uint16_t"
 "perror","stdio.h","CONFIG_NFILE_DESCRIPTORS > 0 && CONFIG_NFILE_STREAMS > 0","void","FAR const char *"
+"pipe","unistd.h","CONFIG_NFILE_DESCRIPTORS > 0","int","int [2]|int*"
 "printf","stdio.h","","int","const char *","..."
 "pthread_attr_destroy","pthread.h","!defined(CONFIG_DISABLE_PTHREAD)","int","FAR pthread_attr_t *"
 "pthread_attr_getinheritsched","pthread.h","!defined(CONFIG_DISABLE_PTHREAD)","int","FAR const pthread_attr_t *","FAR int *"