[PATCH iproute2] include/json_print.h: add includes for `__u32` and `timeval` declarations

[Sergei Trofimovich <slyich@gmail.com>]

Without the change the build fails on `musl` as:

```
../include/json_print.h:100:44: error: unknown type name ‘__u32’
  100 | unsigned int print_range(const char *name, __u32 start, __u32 end);
      |                                            ^~~~~
...
../include/json_print.h:82:30: warning: ‘struct timeval’ declared inside parameter list will not be visible outside of this definition or declaration
   82 | _PRINT_FUNC(tv, const struct timeval *)
      |                              ^~~~~~~
../include/json_print.h:57:45: note: in definition of macro ‘_PRINT_FUNC’
   57 |                                             type value)                 \
      |                                             ^~~~
../include/json_print.h: In function ‘print_tv’:
../include/json_print.h:60:48: error: passing argument 5 of ‘print_color_tv’ from incompatible pointer type [-Wincompatible-pointer-types]
   60 |                                                value);                  \
      |                                                ^~~~~
      |                                                |
      |                                                const struct timeval *
```
---
 include/json_print.h | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/include/json_print.h b/include/json_print.h
index 59edd5b2..c0d6315f 100644
--- a/include/json_print.h
+++ b/include/json_print.h
@@ -8,6 +8,10 @@
 #ifndef _JSON_PRINT_H_
 #define _JSON_PRINT_H_
 
+#include <sys/time.h> /* struct timeval typedef */
+
+#include <asm/types.h> /* __u32 typedef */
+
 #include "json_writer.h"
 #include "color.h"
 
-- 
2.52.0