Handle empty signed data in PKCS7 #886

Job	Run time
openssl-1.0.2u	3m 38s
openssl-1.1.0l	2m 21s
openssl-1.1.1w	3m 2s
openssl-3.0.12	4m 18s
openssl-3.1.4	5m 2s
libressl-3.1.5	3m 3s
libressl-3.2.7	3m 13s
libressl-3.3.6	3m 6s
libressl-3.4.3	3m 44s
libressl-3.5.3	3m 57s
libressl-3.6.3	3m 20s
libressl-3.7.3	4m 9s
libressl-3.8.1	3m 0s
openssl-3.0.12 fips	4m 15s
openssl-3.1.4 fips	5m 29s
openssl-head	5m 22s
openssl-head fips	5m 26s
ruby-versions / Generate Ruby versions	3s
ubuntu-22.04 2.7	1m 25s
ubuntu-22.04 3.0	1m 7s
ubuntu-22.04 3.1	1m 31s
ubuntu-22.04 3.2	1m 14s
ubuntu-22.04 head	1m 10s
ubuntu-22.04 truffleruby	1m 41s
ubuntu-22.04 truffleruby-head	1m 48s
ubuntu-20.04 2.7	1m 31s
ubuntu-20.04 3.0	2m 40s
ubuntu-20.04 3.1	1m 5s
ubuntu-20.04 3.2	1m 30s
ubuntu-20.04 head	1m 10s
ubuntu-20.04 truffleruby-head	2m 10s
macos-latest 2.7	1m 56s
macos-latest 3.0	56s
macos-latest 3.1	1m 0s
macos-latest 3.2	1m 25s
macos-latest head	1m 0s
macos-latest truffleruby-head	3m 51s
windows-latest 2.7	6m 35s
windows-latest 3.0	6m 45s
windows-latest 3.1	5m 39s
windows-latest 3.2	8m 14s
windows-latest ucrt	5m 22s
windows-latest mswin	3m 38s
	2h 12m 51s

Provide feedback