[libgda] mysql: avoid my_bool redefinition

[Daniel Espinosa Ortiz <despinosa src gnome org>]

commit 46c84282902b4589da4d73b8755479851da1a4ae
Author: Daniel Espinosa Ortiz <esodan gmail com>
Date:   Wed Jan 16 13:05:16 2019 -0600

    mysql: avoid my_bool redefinition

 providers/mysql/gda-mysql.h | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)
---
diff --git a/providers/mysql/gda-mysql.h b/providers/mysql/gda-mysql.h
index b1c94609c..316fda5c3 100644
--- a/providers/mysql/gda-mysql.h
+++ b/providers/mysql/gda-mysql.h
@@ -52,8 +52,11 @@ typedef struct {
 
 // Makes back my_bool
 #ifdef MYSQL8
+#ifndef __MY_BOOL__
+#define __MY_BOOL__
 
 typedef _Bool my_bool;
-
 #endif
 #endif
+
+#endif