[GRASS-git] [OSGeo/grass] 2b946e: Fix -Wtype-limits warnings (#2756)

[Nicklas Larsson]

  Branch: refs/heads/main
  Home:   https://github.com/OSGeo/grass
  Commit: 2b946ed8a09d6d4dc057c4a575e3e7f3308cc750
      https://github.com/OSGeo/grass/commit/2b946ed8a09d6d4dc057c4a575e3e7f3308cc750
  Author: Nicklas Larsson <n_larsson at yahoo.com>
  Date:   2023-01-18 (Wed, 18 Jan 2023)

  Changed paths:
    M lib/gis/copy_dir.c
    M vector/v.vol.rst/user1.c

  Log Message:
  -----------
  Fix -Wtype-limits warnings (#2756)

* fix -Wtype-limits warnings (GCC)
* cast before multiplication to prevent potential overflow