[gnome-builder] util: Silence stderr of cat command

[Christian Hergert <chergert src gnome org>]

commit 16584f1810ac9fb2bc87043831d1beb74dbd8c9d
Author: Matthew Leeds <matthew leeds endlessm com>
Date:   Fri Nov 30 15:08:38 2018 -0800

    util: Silence stderr of cat command
    
    Without this patch, I see Builder output on the CLI:
    
    cat: /proc/sys/fs/binfmt_misc/qemu-aarch64: No such file or directory
    cat: /proc/sys/fs/binfmt_misc/qemu-arm: No such file or directory

 src/libide/util/ide-glib.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)
---
diff --git a/src/libide/util/ide-glib.c b/src/libide/util/ide-glib.c
index 05c19b52b..f88f8aaf8 100644
--- a/src/libide/util/ide-glib.c
+++ b/src/libide/util/ide-glib.c
@@ -655,7 +655,8 @@ ide_g_host_file_get_contents (const gchar  *path,
     g_autoptr(IdeSubprocess) subprocess = NULL;
     g_autoptr(GBytes) stdout_buf = NULL;
 
-    launcher = ide_subprocess_launcher_new (G_SUBPROCESS_FLAGS_STDOUT_PIPE);
+    launcher = ide_subprocess_launcher_new (G_SUBPROCESS_FLAGS_STDOUT_PIPE |
+                                            G_SUBPROCESS_FLAGS_STDERR_SILENCE);
     ide_subprocess_launcher_set_run_on_host (launcher, TRUE);
     ide_subprocess_launcher_push_argv (launcher, "cat");
     ide_subprocess_launcher_push_argv (launcher, path);