fix cmakebuild test

write it in a way which is more compatible with older versions of cmake (<3.13)

Also:
fix pzstd compilation (notably on macos)

.gitignore

@@ -27,6 +27,8 @@ tmp*
 dictionary.
 dictionary
 NUL
+cmakebuild/
+install/
 
 # Build artefacts
 contrib/linux-kernel/linux/