[libc] Add dl features in KConfig.

components/libc/Kconfig

@@ -27,6 +27,12 @@ if RT_USING_LIBC && RT_USING_DFS
         bool "Enable AIO"
         default n
     endif
+
+    if RT_USING_MODULE
+    config RT_USING_LIBDL
+        bool "Enable dlopen/dlsym/dlclose feature"
+        default n
+    endif
 endif
 
 config HAVE_SYS_SIGNALS

components/libc/libdl/dlfcn.h

@@ -16,3 +16,4 @@ void *dlsym(void *handle, const char *symbol);
 int dlclose (void *handle);
 
 #endif
+

components/libc/libdl/dlopen.c

@@ -16,7 +16,7 @@
 #include <rtm.h>
 #include <string.h>
 
-#define MODULE_ROOT_DIR		"/module/lib"
+#define MODULE_ROOT_DIR     "/modules"
 
 void* dlopen(const char *filename, int flags)
 {
@@ -53,6 +53,5 @@ void* dlopen(const char *filename, int flags)
 
     return (void*)module;
 }
-
-RTM_EXPORT(dlopen)
+RTM_EXPORT(dlopen);