Backport locking patch from chw #3878

Job	Run time
gcc	14m 0s
msvc	12m 46s
gcc (CFLAGS=-DTCL_NO_DEPRECATED=1)	14m 0s
msvc (CHECKS=nodep)	11m 6s
gcc (--disable-shared)	14m 55s
msvc (OPTS=static)	14m 0s
gcc (--enable-symbols)	11m 36s
msvc (OPTS=symbols)	11m 35s
gcc (--enable-symbols=mem)	16m 57s
msvc (OPTS=symbols STATS=compdbg,memdbg)	17m 28s
gcc (--enable-symbols=all)	16m 47s
	2h 35m 10s

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