Bug#1123915: libxdmcp: Build-Depends: w3m is unnecessary

[Bastian Germann]

Source: libxdmcp
Version: 1:1.1.5-1
Severity: important

w3m is not used during the build. Please drop it.
This would also cut a dependency cycle that libxdmcp is currently
involved in and that keeps packages from being built on loong64.