Fix OSSL_STORE's 'file' loader: make sure peekbuf is initialised
Fix OSSL_STORE's 'file' loader: make sure peekbuf is initialised

This quiets down complaints about the use of uninitialised memory

[extended tests]

Reviewed-by: Rich Salz <c04971a99e5a9ee80eaab4b1deb37e845b0bd697@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/4340)

openssl/openssl,openssl/openssl,openssl/openssl,openssl/openssl,openssl/openssl,openssl/openssl