x509parse_crt() now better handles PEM error situations

Because of new pem_read_buffer() handling of when it writes use_len,
x509parse_crt() is able to better handle situations where a PEM blob
results in an error but the other blobs can still be parsed.
(cherry picked from commit 6417186365f4a73a719fff754fefe8edcef2bc28)
1 file changed