Makefile in the tests directory; ln command needs the "f" switch

[grgoffe]

Describe the bug On a lark, I ran make test and got an error with the ln command. It needs an 'f' in the switch in order to replace any existing link. I checked the other Makefiles and did NOT find any others with this problem.

Here's a snippet of the Makefile; I added the 'f' in the '-sf' switch:

437         [ -f lz4 ] || ln -sf $(PRGDIR)/zstd lz4
438         [ -f unlz4 ] || ln -sf $(PRGDIR)/zstd unlz4

To Reproduce Steps to reproduce the behavior:

1. Downloads data '...'
2. Run '...' with flags '...'
3. Scroll up on the log to '....'
4. See error

Expected behavior The xz link in the tests directory should be successful and not generate an error message.

Screenshots and charts Not needed.

Desktop (please complete the following information):

• OS: Fedora
• Version 42
• Compiler gcc (GCC) 15.0.1 20250325 (experimental)
• Flags [e.g. O2]
• Other relevant hardware specs [e.g. Dual-core]
• Build system Makefile

Additional context Add any other context about the problem here.