don't say "install complete" when it really isn't

Change the recovery UI so that when there is a hboot or radio update
pending (which the user most do a home+back reboot to actually
install), the UI tells them so, instead of saying "Install from sdcard
complete."

firmware.c

@@ -39,6 +39,10 @@ int remember_firmware_update(const char *type, const char *data, int length) {
     return 0;
 }
 
+// Return true if there is a firmware update pending.
+int firmware_update_pending() {
+  return update_data != NULL && update_length > 0;
+}
 
 /* Bootloader / Recovery Flow
  *

firmware.h

@@ -23,6 +23,9 @@
  */
 int remember_firmware_update(const char *type, const char *data, int length);
 
+/* Returns true if a firmware update has been saved. */
+int firmware_update_pending();
+
 /* If an update was saved, reboot into the bootloader now to install it.
  * Returns 0 if no radio image was defined, nonzero on error,
  * doesn't return at all on success...

install.c

@@ -105,7 +105,7 @@ handle_update_script(ZipArchive *zip, const ZipEntry *update_script_entry)
         return INSTALL_ERROR;
     }
 
-    ui_print("Installation complete.\n");
+    LOGI("Installation complete.\n");
     return INSTALL_SUCCESS;
 }
 

recovery.c

@@ -375,7 +375,12 @@ prompt_and_wait()
                     } else if (!ui_text_visible()) {
                         return;  // reboot if logs aren't visible
                     } else {
-                      ui_print("Install from sdcard complete.\n");
+                      if (firmware_update_pending()) {
+                        ui_print("\nReboot via home+back or menu\n"
+                                 "to complete installation.\n");
+                      } else {
+                        ui_print("\nInstall from sdcard complete.\n");
+                      }
                     }
                     break;
             }