Add docbook-xsl build-dependency.

8 jobs for master in 8 minutes and 6 seconds (queued for 3 seconds)
Status Job ID Name Coverage
  Build
passed #326851
build

00:03:04

 
  Test
passed #326856
autopkgtest

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passed #326857
blhc

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passed #326855
lintian

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passed #326858
piuparts

00:04:59

passed #326854
reprotest

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passed #326853
test-build-all

00:03:04

passed #326852
test-build-any

00:03:32