BUILD: Fix build by including haproxy/global.h

In srv/version.c, fix build by including haproxy/global.h, so that
REGISTER_BUILD_OPTS is properly defined.
diff --git a/src/version.c b/src/version.c
index bf67efa..e7bb748 100644
--- a/src/version.c
+++ b/src/version.c
@@ -4,6 +4,7 @@
  * code version.
  */
 
+#include <haproxy/global.h>
 #include <haproxy/version.h>
 
 /* These ones are made variables and not constants so that they are stored into