Fix encoding crash when LANG environment is empty #1759

Job	Run time
ruby-versions / Generate Ruby versions	4s
ruby-versions / Generate Ruby versions	4s
test (2.7)	2m 15s
test (2.7)	2m 15s
test (3.0)	2m 0s
test (3.0)	10m 14s
test (3.1)	2m 8s
test (3.1)	10m 14s
test (3.2)	1m 36s
test (3.2)	1m 36s
test (3.3)	1m 41s
test (3.3)	1m 41s
test (3.4)	1m 43s
test (3.4)	1m 43s
test (debug)	6m 2s
test (debug)	10m 14s
test (head)	1m 36s
test (head)	10m 13s
	1h 7m 19s

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