Update options on reconfigure when default_options changes #13845

Job	Run time
Arch / PyPy	26m 45s
Ubuntu Rolling (gcc, g++)	22m 57s
Ubuntu Rolling (--unity=on -Ddefault_library=static, --no-unittests, gcc, g++)	23m 7s
Arch Linux	28m 40s
Ubuntu Rolling (-Ddefault_library=both, --no-unittests, gcc, g++)	22m 25s
CUDA (on Arch)	9m 22s
Ubuntu Rolling (clang, clang++)	29m 23s
Ubuntu Rolling (--unity=on, --no-unittests, clang, clang++)	18m 23s
Fedora	21m 19s
Ubuntu Rolling (--cross ubuntu-armhf.json --cross linux-mingw-w64-64bit.json, 0, gcc, g++)	20m 21s
OpenSUSE	24m 53s
Ubuntu Rolling (--cross ubuntu-armhf.json --cross linux-mingw-w64-64bit.json, --unity=on, gcc, g++)	20m 8s
Ubuntu Bionic	22m 0s
	4h 49m 43s

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