gnucash unstable: Set GNC_VCS at build time instead of when making the tarball.

[John Ralls]

Updated	 via  https://github.com/Gnucash/gnucash/commit/192a3c3d (commit)
	from  https://github.com/Gnucash/gnucash/commit/ba3bf37d (commit)



commit 192a3c3d2b18e5440c9faa4942d577adf1aeb0c0
Author: John Ralls <jralls at ceridwen.us>
Date:   Mon Apr 9 15:10:25 2018 -0700

    Set GNC_VCS at build time instead of when making the tarball.
    
    Because the tarball is always made from a VCS repo.



Summary of changes:
 gnucash/CMakeLists.txt               | 4 ++++
 gnucash/gnome-utils/CMakeLists.txt   | 6 +++++-
 libgnucash/core-utils/CMakeLists.txt | 1 -
 3 files changed, 9 insertions(+), 2 deletions(-)