Build Warning with -Wunused-return on gcc

[inventor500]

Describe the bug
When building with -std=c++17 and -Wunused-return, gcc issues a warning.
I noticed this when building the Arch Linux build, but I reproduced it when building the dev branch as well.

I read the note about static analysis in the contribution guidelines. Using something like std::ignore would clarify that the return value here is irrelevant.

To Reproduce
Steps to reproduce the behavior (with make):

1. cd contrib/pzstd
2. Comment out setting PZSTD_CXX_STD in Makefile
3. export CPPFLAGS="-Wunused-result"
4. export CXXFLAGS="-std=c++17"
5. make

Expected behavior
There should be no compiler warnings when building.

Screenshots and charts

Desktop (please complete the following information):

• OS: Arch Linux with kernel 6.10.3-zen1-2-zen
• Version: 1.5.6 and dev branch
• Compiler: gcc 14.2.1
• Build system: CMake

Additional context
Add any other context about the problem here.