[fvwmorg/fvwm] 1c0a7a: Cleanup some minor issues with build tools.

[Jaimos]

  Branch: refs/heads/js/build-cleanup
  Home:   https://github.com/fvwmorg/fvwm
  Commit: 1c0a7a945b08ec853a01bfe53b7dc726ef6418d2
      
https://github.com/fvwmorg/fvwm/commit/1c0a7a945b08ec853a01bfe53b7dc726ef6418d2
  Author: Jaimos <jaimosskril...@boisestate.edu>
  Date:   2021-06-05 (Sat, 05 Jun 2021)

  Changed paths:
    M Makefile.am
    M configure.ac
    M default-config/Makefile.am
    M modules/Makefile.am

  Log Message:
  -----------
  Cleanup some minor issues with build tools.

  * Update ./configure --help to correctly state that --enable-mandoc
    is needed to build man pages.
  * Update make uninstall to remove the directories and links created
    during the install.
  * Remove *_BUGADDR from configure.ac.