serve_image: do not include error.h

serve_image does not use anything from it and it is not available with all
C libraries, e.g. musl.

Signed-off-by: Jörg Krause <joerg.krause@embedded.rocks>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>
diff --git a/serve_image.c b/serve_image.c
index 38549a1..4f0e946 100644
--- a/serve_image.c
+++ b/serve_image.c
@@ -3,7 +3,6 @@
 
 #include <time.h>
 #include <errno.h>
-#include <error.h>
 #include <netdb.h>
 #include <stdio.h>
 #include <stdlib.h>