[gtk/new-sysprof] fixup a counting error

[Matthias Clasen <matthiasc src gnome org>]

commit 7039f313910fc00c1937d09950fac17f516b0a96
Author: Matthias Clasen <mclasen redhat com>
Date:   Fri Aug 21 13:39:38 2020 -0400

    fixup a counting error
    
    Remember: 1, 2, 3, _4_, 5...

 testsuite/performance/test-performance.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)
---
diff --git a/testsuite/performance/test-performance.c b/testsuite/performance/test-performance.c
index 2a8b6d902c..b6b53de2d1 100644
--- a/testsuite/performance/test-performance.c
+++ b/testsuite/performance/test-performance.c
@@ -135,10 +135,10 @@ main (int argc, char *argv[])
       child_argv[1] = (char *)"--force";
       child_argv[2] = (char *)"--use-trace-fd";
       child_argv[3] = name;
-      child_argv[5] = (char *)"--";
+      child_argv[4] = (char *)"--";
       for (i = 0; i + 1 < argc; i++)
-        child_argv[6 + i] = argv[i + 1];
-      child_argv[6 + argc - 1] = NULL;
+        child_argv[5 + i] = argv[i + 1];
+      child_argv[5 + argc - 1] = NULL;
 
       launcher = g_subprocess_launcher_new (0);
       g_subprocess_launcher_setenv (launcher, "GTK_DEBUG_AUTO_QUIT", "1", TRUE);