configure.ac: use variable for dvdnav version

4 jobs for versioning in 2 minutes and 48 seconds (queued for 1 second)
Status Job ID Name Coverage
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passed #361922
amd64 debian
build-debian

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passed #361923
macos
build-macos

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win32 amd64 debian
build-win32

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passed #361924
win64 amd64 debian
build-win64

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