[gimp] tools, fix implicit declaration of function atoi warning

[Jehan <jehanp src gnome org>]

commit bed5fe37d8845f53f8422d6e8c4e23d89cb48c55
Author: lillolollo <4179-lillolollo users noreply gitlab gnome org>
Date:   Sat Nov 30 02:06:30 2019 +0000

    tools, fix implicit declaration of function atoi warning
    
    (cherry picked from commit 1ca3d99fbc62720054e31d7d489aaeb690b52e96)

 tools/gimp-debug-resume.c | 1 +
 1 file changed, 1 insertion(+)
---
diff --git a/tools/gimp-debug-resume.c b/tools/gimp-debug-resume.c
index f5294df583..2aac3b3d49 100644
--- a/tools/gimp-debug-resume.c
+++ b/tools/gimp-debug-resume.c
@@ -7,6 +7,7 @@
 #include <tchar.h>
 #include <tlhelp32.h>
 #include <stdio.h>
+#include <stdlib.h>
 
 static BOOL
 resume_process (DWORD dwOwnerPID)