[gimp] plug-ins: headers only needed with the Sendmail-email plugin.

[Jehan Pagès <jehanp src gnome org>]

commit dd4848e680c52747d03dda52e3c11c4064c960f0
Author: Jehan <jehan girinstud io>
Date:   Thu Feb 2 19:44:28 2017 +0100

    plug-ins: headers only needed with the Sendmail-email plugin.

 plug-ins/common/mail.c |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)
---
diff --git a/plug-ins/common/mail.c b/plug-ins/common/mail.c
index 61ce7be..d205b5a 100644
--- a/plug-ins/common/mail.c
+++ b/plug-ins/common/mail.c
@@ -32,8 +32,10 @@
 
 #include <string.h>
 
+#ifdef SENDMAIL
 #include <sys/types.h>
 #include <sys/wait.h>
+#endif
 
 #include <glib/gstdio.h>