gnucash master: Prevent libstdc++ copysign declaration error on Win32.

[John Ralls]

Updated	 via  https://github.com/Gnucash/gnucash/commit/2a42078e (commit)
	from  https://github.com/Gnucash/gnucash/commit/8654cb86 (commit)



commit 2a42078e9a6ca920a342264b5caf4c8571316cbd
Author: John Ralls <jralls at ceridwen.us>
Date:   Sat May 30 15:18:18 2020 -0700

    Prevent libstdc++ copysign declaration error on Win32.



Summary of changes:
 gnucash/gnucash-core-app.hpp | 3 +++
 1 file changed, 3 insertions(+)