[PATCH-for-9.1?] qapi/util: Include missing 'qapi/error.h' header

["Philippe Mathieu-Daudé" <philmd@linaro.org>]

qapi_enum_parse() uses the Error type which is
declared in "qapi/error.h". Include "qapi/error.h"
in order to avoid:

  include/qapi/util.h:27:30: error: unknown type name 'Error'
                    int def, Error **errp);
                             ^

Note we include it after the QEnumLookup declaration
to avoid:

  In file included from include/qapi/error.h:275:
  qapi/qapi-types-error.h:30:14: error: unknown type name 'QEnumLookup'
  extern const QEnumLookup QapiErrorClass_lookup;
               ^

Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
---
 include/qapi/util.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/include/qapi/util.h b/include/qapi/util.h
index b8254247b8..568f31ac9e 100644
--- a/include/qapi/util.h
+++ b/include/qapi/util.h
@@ -22,6 +22,8 @@ typedef struct QEnumLookup {
     const int size;
 } QEnumLookup;
 
+#include "qapi/error.h"
+
 const char *qapi_enum_lookup(const QEnumLookup *lookup, int val);
 int qapi_enum_parse(const QEnumLookup *lookup, const char *buf,
                     int def, Error **errp);
-- 
2.45.2