Linux 6.6 compat: fix uninitialized timespec for LLVM

[arter97]

Commit fe9d409 ("Linux 6.6 compat: use inode_get/set_ctime*(...)") adds compatibility with Linux v6.6 but people using the LLVM toolchain for their kernels encounter kabi check failure due to uninitialized ts:

/var/lib/dkms/zfs/2.2.1/build/build/inode_set_ctime_to_ts/inode_set_ctime_to_ts.c:79:30: error: variable 'ts' is uninitialized when used here [-Werror,-Wuninitialized]
   79 |                 inode_set_ctime_to_ts(&ip, ts);
      |                                            ^~
/var/lib/dkms/zfs/2.2.1/build/build/inode_set_ctime_to_ts/inode_set_ctime_to_ts.c:76:3: note: variable 'ts' is declared here
   76 |                 struct timespec64 ts;
      |                 ^

Similar incident was fixed with commit 3e5d41d ("config/kernel-inode-times: initialize timespec").

Follow it and initialize ts.

Fixes: fe9d409 ("Linux 6.6 compat: use inode_get/set_ctime*(...)")

Motivation and Context

Using the latest OpenZFS with Linux v6.6 built with LLVM 17 toolchain breaks autoconf and therefore the kernel module build.

Description

Similar issue was handled before. This commit follows the previous commit's patch and initializes struct timespec64 ts for LLVM compiler.

How Has This Been Tested?

Build-tested with Linux v6.6 using the LLVM 17 toolchain and checked ZFS module loads and behaves correctly.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Performance enhancement (non-breaking change which improves efficiency)
• Code cleanup (non-breaking change which makes code smaller or more readable)
• Breaking change (fix or feature that would cause existing functionality to change)
• Library ABI change (libzfs, libzfs_core, libnvpair, libuutil and libzfsbootenv)
• Documentation (a change to man pages or other documentation)

Checklist:

• My code follows the OpenZFS code style requirements.
• I have updated the documentation accordingly.
• I have read the contributing document.
• I have added tests to cover my changes.
• I have run the ZFS Test Suite with this change applied.
• All commit messages are properly formatted and contain Signed-off-by.

[arter97]

Welp, didn't know #15558 was active.

@kentdobias, @tonyhutter Dunno how nit-picky those configuration code should be, but I believe memset is more inline with existing code.

Feel free to kang my commit message and the memset part if you deem it's cleaner.

[behlendorf]

Thanks for the fix, we've gone ahead and merged #15558 for this.