src/libs/types.h: include sys/types.h (#273)

Include sys/types.h to avoid the following uclibc build failure since
version 5.52 and
2d6716a:

In file included from libs/base64.h:25,
                 from libs/base64.c:23:
libs/types.h:30:9: error: unknown type name 'ssize_t'
   30 | typedef ssize_t sz;
      |         ^~~~~~~

Fixes:
 - http://autobuild.buildroot.org/results/24498049d7beb4afaaf9f9a0c2fc0bcd26a3ee04

Signed-off-by: Fabrice Fontaine <[email protected]>

src/libs/types.h

@@ -24,6 +24,7 @@
 #include <stdio.h>
 #include <stdbool.h>
 #include <stdint.h>
+#include <sys/types.h>
 
 
 typedef long long sll;