calloc can return NULL but xcalloc cannot. From Coverity CID 291881,
authordtucker <dtucker@openbsd.org>
Sun, 12 Mar 2023 09:41:18 +0000 (09:41 +0000)
committerdtucker <dtucker@openbsd.org>
Sun, 12 Mar 2023 09:41:18 +0000 (09:41 +0000)
commite3b8965f5c23f4c5342d47edbce78d8b7d1ef76c
treed3d2bfa34cb8d7803bb493714a11afa877ca63ba
parenta3faff3e11072d8e67b5add7835fdbedd459da0b
calloc can return NULL but xcalloc cannot.  From Coverity CID 291881,
ok djm@
usr.bin/ssh/sftp.c