zstd

Summary This PR updates to select for RISC-V builds when both and are defined. Motivation indicates support for misaligned loads/stores in main memory. For these targets, using method 2 enables direct unaligned memory access in . References GCC Zicclsm RVA20U64 specification Changes Updated the default selection logic: when Keep existing GCC fallback: for other GCC targets No changes to behavior when is explicitly set by the build system. Validation Verified the updated preprocessor branch compiles cleanly in . No linter issues reported for the modified file. Benchmark Data (Compression Speed) Method vs Method 0 Method 2 +74% Method 1 +39% Method 0 - Data screenshot

According to the mmap docs is returned upon error: On success, mmap() returns a pointer to the mapped area. On error, the value MAP_FAILED (that is, (void *) -1) is returned, and errno is set to indicate the error. Update mmap error validation to check for instead of NULL. POSIX specifies that mmap returns (-1) on failure. Reported-by: Clang 21 Static Analyzer

Align the declarations of and in with their definitions. The previous declarations caused an attribute mismatch between the header and the definitions, which can lead to incorrect compiler assumptions under certain toolchains and optimization levels.