[dmodule] 补充头文件 (#5602)

* add references

* [dmodule] add <fcntl.h>

components/libc/compilers/armlibc/README.md

@@ -1,3 +1,5 @@
 # ARMLIB (Keil-MDK) porting for RT-Thread
 
-https://www.keil.com/support/man/docs/armlib/
+https://www.keil.com/support/man/docs/armlib/
+
+https://www.keil.com/support/man/docs/armlib/armlib_chr1358938918041.htm

components/libc/posix/libdl/dlmodule.c

@@ -15,6 +15,7 @@
 #include "dlelf.h"
 
 #ifdef RT_USING_POSIX_FS
+#include <fcntl.h>
 #include <unistd.h>
 #include <sys/stat.h>
 #include <sys/statfs.h>