Add documentation about env variables that can influence configure.

Description

Add documentation about env variables that can influence configure.

assigned to @iamashwin99

mentioned in merge request !2294 (merged)

added 1 commit

• 77b19a81 - include -lelpa in a comment

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approved this merge request

merged

mentioned in commit efab2e80

changed milestone to %14.0

added Build system Documentation in Changelog labels