[PATCH] Cygwin: Fix compatibility with GCC 15

[Thirumalai Nagalingam]

Hello,

Please find my patch attached for review.

Summary of Changes:

- GCC 15 defaults to `-std=gnu23`, causing build failures in `test suite`
  due to outdated C function declarations.
- This patch updates sbrk01.c and symlink01.c for GCC 15 compatibility.
- These changes were not included in my previous patch.

Thanks & regards
Thirumalai Nagalingam

0001-Cygwin-testsuite-Fix-compatibility-with-GCC-15.patch
Description: 0001-Cygwin-testsuite-Fix-compatibility-with-GCC-15.patch