gnucash master: Revert "Set C and C++ standards the modern Cmake way, and set C++ to C++17."

[John Ralls]

Updated	 via  https://github.com/Gnucash/gnucash/commit/58cfb58b (commit)
	from  https://github.com/Gnucash/gnucash/commit/b5afd2e3 (commit)



commit 58cfb58b9cfe5d1fdbaec0c266d9247f9eb5134d
Author: John Ralls <jralls at ceridwen.us>
Date:   Tue Oct 8 21:05:00 2019 -0700

    Revert "Set C and C++ standards the modern Cmake way, and set C++ to C++17."
    
    This reverts commit b5afd2e319b0f06697c83806e85dd15fab508e5b.
    
    Our baseline distro, Ubuntu 18.04, provides boost 1.65 and boost 1.67
    is required for building with C++17 because the boost::locale developer
    hung on to auto_ptr 6 years longer than he should have.



Summary of changes:
 CMakeLists.txt      | 14 +++++---------
 README.dependencies |  8 +++-----
 2 files changed, 8 insertions(+), 14 deletions(-)