gcal: fix build on Ventura

[iMichka]

Fixes:
tty.c:858:9: error: call to undeclared function 'ioctl'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration

The texinfo error is also on Ventura so fix it too (not just on Linux)

• Have you followed the guidelines for contributing?
• Have you ensured that your commits follow the commit style guide?
• Have you checked that there aren't other open pull requests for the same formula update/change?
• Have you built your formula locally with brew install --build-from-source <formula>, where <formula> is the name of the formula you're submitting?
• Is your test running fine brew test <formula>, where <formula> is the name of the formula you're submitting?
• Does your build pass brew audit --strict <formula> (after doing brew install --build-from-source <formula>)? If this is a new formula, does it pass brew audit --new <formula>?

---

[SMillerDev]

Linux:

  fseeko.c: In function 'rpl_fseeko':
  fseeko.c:110:4: error: #error "Please port gnulib fseeko.c to your platform! Look at the code in fseeko.c, then report this to bug-gnulib."
    110 |   #error "Please port gnulib fseeko.c to your platform! Look at the code in fseeko.c, then report this to bug-gnulib."
        |    ^~~~~

[github-actions]

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