gnucash maint: Use cmake_symbol_check to test for AB_Banking_RuntimeConfig_SetCharValue

[John Ralls]

Updated	 via  https://github.com/Gnucash/gnucash/commit/adae341d (commit)
	from  https://github.com/Gnucash/gnucash/commit/2a6a4e34 (commit)



commit adae341def2398891a3b6a9c0af0e59417debfcd
Author: John Ralls <jralls at ceridwen.us>
Date:   Sun Aug 11 09:43:27 2019 -0700

    Use cmake_symbol_check to test for AB_Banking_RuntimeConfig_SetCharValue
    
    instead of relying on AQBanking versions.



Summary of changes:
 CMakeLists.txt                           | 8 ++++++++
 common/config.h.cmake.in                 | 3 +++
 gnucash/import-export/aqb/gnc-ab-utils.c | 5 +----
 3 files changed, 12 insertions(+), 4 deletions(-)