textops: properly initialize new tr_param_t object

[lyokha]

Just memset() this to 0.

Without this kamailio segfaults when running fparam_free_restore() on a variable that contains transformations immediately after creation, because field next of the transformation contains garbage.

In my case this was variable which contained re.subst transformation. And below is the top of the backtrace.

#0  0x00000000005cba17 in tr_param_free (tp=0x292873257325203a) at core/pvapi.c:1804
#1  0x00000000005cb677 in tr_destroy (t=0x7f6387ed0c40) at core/pvapi.c:1742
#2  0x00000000005cb9c1 in tr_free (t=0x0) at core/pvapi.c:1786
#3  0x00000000005ca194 in pv_spec_destroy (spec=0x7f6387ed0b80) at core/pvapi.c:1570
#4  0x00000000005ca1b7 in pv_spec_free (spec=0x7f6387ed0b80) at core/pvapi.c:1578
#5  0x0000000000541820 in fparam_free_contents (fp=0x7f6387ed0ae0) at core/sr_module.c:1334
#6  0x0000000000541898 in fparam_free_restore (param=0x7f6387ed1168) at core/sr_module.c:1364

Pre-Submission Checklist

• Commit message has the format required by CONTRIBUTING guide
• Commits are split per component (core, individual modules, libs, utils, ...)
• Each component has a single commit (if not, squash them into one commit)
• No commits to README files for modules (changes must be done to docbook files
  in doc/ subfolder, the README file is autogenerated)

Type Of Change

• Small bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds new functionality)
• Breaking change (fix or feature that would change existing functionality)

Checklist:

• PR should be backported to stable branches
• Tested changes locally
• Related to issue #XXXX (replace XXXX with an open issue number)

Description

[miconda]

Thanks! Applied it manually because the git log message was not properly using module prefix, only the pull request was with the title like it should have been the git log.