fix: BASE > 3.14 expressed as ifdef BASE_3_15. #221

Job	Run time
7.0/ubuntu-20.04/gcc/default/	3m 13s
7.0/ubuntu-20.04/gcc/static/	1m 38s
3.15/ubuntu-20.04/gcc/default/	2m 16s
3.14/ubuntu-20.04/gcc/default/	3m 8s
7.0/ubuntu-20.04/gcc/static/CMD_CXXFLAGS=-std=c++11	3m 25s
7.0/ubuntu-20.04/clang/default/CMD_CXXFLAGS=-std=c++11	2m 18s
7.0/ubuntu-20.04/gcc/default4.10/	3m 43s
7.0/ubuntu-20.04/gcc/default4.9/	3m 35s
7.0/ubuntu-20.04/gcc-8/default/	1m 55s
7.0/ubuntu-20.04/clang/default/	1m 36s
7.0/ubuntu-latest/gcc/default/	2m 27s
	29m 14s

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