apps/openssl: make index.txt errors more verbose

[FlorianMickler]

openssl ca was a little bit too silent, when it couldnt parse index.txt ...

steps to reproduce: create index.txt with

echo "" > index.txt

which creates

hexdump index.txt
0000000 000a
0000001

-> Trivial change, tested with openssl ca to sign a csr
-> the ocsp and svr changes were only compile tested by me, but seemed to make sense. ?

Checklist

[FlorianMickler]

https://superuser.com/questions/1327848/openssl-ca-fails-after-password-without-error-message

[FlorianMickler]

Hey, this is a trivial thing that has bitten at least two people in the past. Anyone up to merging this or redoing this? Should be a no-brainer.
This wasted so much time on my side that it would be really helpful for others to have this simple message in. I actually dug into the source code to find out why it was not working, because i was getting zero clue!

[paulidale]

Slipped through the gaps I suspect.

[t8m]

I am sorry but unfortunately this is outside of what we usually consider as acceptable under CLA: trivial. Could you please submit a CLA? https://www.openssl.org/policies/cla.html

[FlorianMickler]

I just submitted my ICLA. Do I need to ammend the commit description?

[paulidale]

You'll need to remove the CLA: trivial line from each commit.