Merge core-8-6-branch #420

Job	Run time
test (gcc)	3m 47s
build (gcc)	1m 50s
build (gcc, CFLAGS=-DTK_NO_DEPRECATED=1)	1m 40s
build (gcc, --disable-xft)	1m 42s
test (gcc, --disable-xft)	4m 5s
test (gcc, --enable-symbols)	3m 44s
build (gcc, --disable-xss)	2m 19s
build (gcc, --enable-symbols)	2m 3s
build (clang)	1m 57s
build (clang, CFLAGS=-DTK_NO_DEPRECATED=1)	1m 53s
build (clang, --disable-xft)	2m 13s
build (clang, --disable-xss)	2m 8s
build (clang, --enable-symbols)	1m 30s
	30m 51s

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