Fix issues addressed by static analysis

[yosuke-wolfssl]

This PR fixes the following minor issues:

• Fix Mac comparison in VerifyMac for HMAC failure case
• Delete the incorrect statement in GetOpenSshKey
• Fix cursor mode handling in wolfSSH_DoControlSeq

Addressed by f_520, f_521 and f_522

[Copilot]

Pull request overview

This pull request addresses a few static-analysis findings by tightening error handling in MAC verification, removing a stray/incorrect assignment in OpenSSH key parsing, and fixing CSI cursor-position handling in the Windows terminal code path.

Changes:

• Ensure VerifyMac() only performs the constant-time MAC comparison when HMAC computation succeeded, preserving the underlying HMAC error on failure.
• Remove an incorrect idx = 0; assignment in GetOpenSshKey()’s private-key parsing path.
• Fix CSI H cursor positioning to treat 0/omitted row/column arguments as 1 before applying the Linux(1,1) ↔ Windows(0,0) offset.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
src/wolfterm.c	Fixes CSI H cursor move argument defaults to avoid unsigned underflow and to align with expected terminal semantics.
src/internal.c	Fixes static-analysis issues in OpenSSH key parsing and MAC verification error handling.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.