ignore Thread creation error #1015

Job	Run time
make (check, --enable-shared --enable-load-relative)	7m 45s
make (check, i686)	11m 41s
make (check, cppflags=-DVM_CHECK_MODE)	8m 32s
make (check, --disable-yjit)	7m 56s
make (check, ubuntu-24.04, capi)	10m 5s
make (test-bundler-parallel, 50)	24m 43s
make (test-bundled-gems)	19m 51s
make-ibm	0s
Ubuntu result	2s
	1h 30m 35s

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