Fix 6 extentedcommands declaration warnings

Signed-off-by: Tanguy Pruvot <tanguy.pruvot@gmail.com>
diff --git a/extendedcommands.c b/extendedcommands.c
index 6799b2d..f3542b7 100644
--- a/extendedcommands.c
+++ b/extendedcommands.c
@@ -641,8 +641,6 @@
     return 0 == stat(EXTENDEDCOMMAND_SCRIPT, &file_info);
 }
 
-void process_volumes();
-
 int edify_main(int argc, char** argv) {
     load_volume_table();
     process_volumes();
diff --git a/extendedcommands.h b/extendedcommands.h
index a016b84..101552f 100644
--- a/extendedcommands.h
+++ b/extendedcommands.h
@@ -47,3 +47,13 @@
 int has_datadata();
 
 void handle_failure(int ret);
+
+void process_volumes();
+
+int extendedcommand_file_exists();
+
+void show_install_update_menu();
+
+int confirm_selection(const char* title, const char* confirm);
+
+int run_and_remove_extendedcommand();