Fix the remote-sim.c build

My earlier patch to move gdb_argv broke the remote-sim.c build.  This
patch fixes the bug.  I'm checking it in.
diff --git a/gdb/remote-sim.c b/gdb/remote-sim.c
index 3637fdb..39bddec 100644
--- a/gdb/remote-sim.c
+++ b/gdb/remote-sim.c
@@ -44,6 +44,7 @@
 #include "gdbsupport/byte-vector.h"
 #include "memory-map.h"
 #include "remote.h"
+#include "gdbsupport/buildargv.h"
 
 /* Prototypes */