[gnome-builder] gdbwire: fix format string error when compiling with clang

[Christian Hergert <chergert src gnome org>]

commit 53008a290eb04f3826c6948938fc170caa3d71e4
Author: Ting-Wei Lan <lantw src gnome org>
Date:   Sat Jan 6 12:52:45 2018 +0800

    gdbwire: fix format string error when compiling with clang
    
    https://bugzilla.gnome.org/show_bug.cgi?id=791923

 src/plugins/gdb/gdbwire.c |    6 +++++-
 src/plugins/gdb/gdbwire.h |    6 +++++-
 2 files changed, 10 insertions(+), 2 deletions(-)
---
diff --git a/src/plugins/gdb/gdbwire.c b/src/plugins/gdb/gdbwire.c
index 167e52d..bc8f64f 100644
--- a/src/plugins/gdb/gdbwire.c
+++ b/src/plugins/gdb/gdbwire.c
@@ -569,7 +569,11 @@ enum gdbwire_logger_level {
  * Any additional format arguments.
  */
 void gdbwire_logger_log(const char *file, int line,
-        enum gdbwire_logger_level level, const char *fmt, ...);
+        enum gdbwire_logger_level level, const char *fmt, ...)
+#ifdef __GNUC__
+        __attribute__((__format__(__printf__, 4, 5)))
+#endif
+        ;
 
 /* The macros intended to be used for logging */
 #define gdbwire_debug(fmt, ...)(gdbwire_logger_log(__FILE__, __LINE__, \
diff --git a/src/plugins/gdb/gdbwire.h b/src/plugins/gdb/gdbwire.h
index 8f72527..a178f12 100644
--- a/src/plugins/gdb/gdbwire.h
+++ b/src/plugins/gdb/gdbwire.h
@@ -330,7 +330,11 @@ enum gdbwire_logger_level {
  * Any additional format arguments.
  */
 void gdbwire_logger_log(const char *file, int line,
-        enum gdbwire_logger_level level, const char *fmt, ...);
+        enum gdbwire_logger_level level, const char *fmt, ...)
+#ifdef __GNUC__
+        __attribute__((__format__(__printf__, 4, 5)))
+#endif
+        ;
 
 /* The macros intended to be used for logging */
 #define gdbwire_debug(fmt, ...)(gdbwire_logger_log(__FILE__, __LINE__, \