[PATCH-for-5.2] qapi/error: Make error_vprepend() static

["Philippe Mathieu-Daudé" <philmd@redhat.com>]

error_vprepend() is only used by util/error.c where it is
defined. Make it static to reduce its scope.

Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
---
 include/qapi/error.h | 6 ------
 util/error.c         | 6 +++++-
 2 files changed, 5 insertions(+), 7 deletions(-)

diff --git a/include/qapi/error.h b/include/qapi/error.h
index 7932594dce..fa2308dedd 100644
--- a/include/qapi/error.h
+++ b/include/qapi/error.h
@@ -384,12 +384,6 @@ void error_propagate(Error **dst_errp, Error *local_err);
 void error_propagate_prepend(Error **dst_errp, Error *local_err,
                              const char *fmt, ...);
 
-/*
- * Prepend some text to @errp's human-readable error message.
- * The text is made by formatting @fmt, @ap like vprintf().
- */
-void error_vprepend(Error *const *errp, const char *fmt, va_list ap);
-
 /*
  * Prepend some text to @errp's human-readable error message.
  * The text is made by formatting @fmt, ... like printf().
diff --git a/util/error.c b/util/error.c
index b6c89d1412..3990b741ff 100644
--- a/util/error.c
+++ b/util/error.c
@@ -121,7 +121,11 @@ void error_setg_file_open_internal(Error **errp,
                               "Could not open '%s'", filename);
 }
 
-void error_vprepend(Error *const *errp, const char *fmt, va_list ap)
+/*
+ * Prepend some text to @errp's human-readable error message.
+ * The text is made by formatting @fmt, @ap like vprintf().
+ */
+static void error_vprepend(Error *const *errp, const char *fmt, va_list ap)
 {
     GString *newmsg;
 
-- 
2.21.3