Use more widely supported options for the "tr" command line utility b…y removing the use of the character class representation option. [:space:] => "\t\r\n\v\f"

[master-nevi]

Reference comment: #2305 (comment)

Update to change: #2537

Original problem:

Add support for Synology routers while using dnsapi/dns_freedns.sh. Synology router scripting stacks do not have a version of the "tr" command line utility that supports character class representation option i.e. the "[:space:]" :

tr -d "[:space:]" should be replaced with tr -d "\t\r\n\v\f" inside of dnsapi/dns_freedns.sh for better support across embedded linux systems and routers.

[dkerr64]

@master-nevi @Neilpang Guys, there is still a problem here. I thought I was clear. We need to include a blank space within the quoted string... tr -d " \t\r\n\v\f"
Look carefully and you will see a blank space after the first quote. This was missing from this PR you merged. If you want me to do it then that is fine, but I cannot do it until next week as I am traveling.

[Neilpang]

Done.

[dkerr64]

Done.

Thank you @Neilpang though you also need to do it at line 352 as well as 306...
https://github.com/Neilpang/acme.sh/blob/18ad01533b3b5d0cf51f9e72464940e7a080d880/dnsapi/dns_freedns.sh#L352

[Neilpang]

@dkerr64
fixed. thanks.

[dkerr64]

@dkerr64
fixed. thanks.

@Neilpang Thank You.

[master-nevi]

Thank you @Neilpang and @dkerr64 . I've verified that everything is still working as expected on my end with this latest change.