build: update gnulib submodule to latest

* src/common.h (get_directory_entries):
Add _GL_ATTRIBUTE_MALLOC _GL_ATTRIBUTE_DEALLOC_FREE.
Problem found by gcc -Wsuggest-attribute=malloc and
current Gnulib.

gnulib

@@ -1 +1 @@
-Subproject commit 783f2967e23e6481941c1bf1e73897c66cb4195a
+Subproject commit bce94c07f9220c0a12d568f06674cb394556c64a

src/common.h

@@ -499,7 +499,8 @@ enum dump_status
 void add_exclusion_tag (const char *name, enum exclusion_tag_type type,
 			bool (*predicate) (int));
 bool cachedir_file_p (int fd);
-char *get_directory_entries (struct tar_stat_info *st);
+char *get_directory_entries (struct tar_stat_info *st)
+  _GL_ATTRIBUTE_MALLOC _GL_ATTRIBUTE_DEALLOC_FREE;
 
 void create_archive (void);
 void pad_archive (off_t size_left);