unpackers: check errors from close() too

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
diff --git a/include/libbb.h b/include/libbb.h
index a02355c..dca14b4 100644
--- a/include/libbb.h
+++ b/include/libbb.h
@@ -631,6 +631,9 @@
 extern void xwrite_str(int fd, const char *str) FAST_FUNC;
 extern void xopen_xwrite_close(const char* file, const char *str) FAST_FUNC;
 
+/* Close fd, but check for failures (some types of write errors) */
+extern void xclose(int fd) FAST_FUNC;
+
 /* Reads and prints to stdout till eof, then closes FILE. Exits on error: */
 extern void xprint_and_close_file(FILE *file) FAST_FUNC;