Fix coverity issues #446

Job	Run time
check_update	1m 5s
basic_clang	10s
basic_gcc	20s
check-ansi	2m 0s
minimal	2m 15s
no-deprecated	18s
no-shared (ubuntu-latest)	21s
address_ub_sanitizer	11m 11s
EC_POINTs_api_test	19m 22s
no-shared (macos-latest)	2m 23s
buildtest	6m 46s
enable_non-default_options	16s
external-test-pyca (1.51.0, 3.9)	1m 24s
fips_and_ktls	16s
legacy	3m 36s
memory_sanitizer	25m 9s
no-legacy	21s
non-caching	4m 24s
ntls_address_ub_sanitizer	9m 32s
ntls_memory_sanitizer	17m 4s
out-of-source-and-install (ubuntu-latest)	24s
phe_test	13s
symbol_prefix-test	1m 9s
out-of-source-and-install (macos-latest)	3m 16s
threads_sanitizer	11s
ntls-with-fips	27s
ntls-without-sm234	17s
sm2-threshold-test	10s
smtc_and_ntls	19s
zkp-build-test	10s
	1h 54m 49s

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