Canonical Naming and Typos

Use canonical, consistently formatted identifiers across code and build files, and verify every variable/option name is spelled exactly as the build system expects.

Apply this checklist: 1) Canonical token per platform/arch: follow the established external style the project aligns with (e.g., for Loongarch, prefer loongarch consistently rather than loongarch64 for directory/file/class naming). 2) Consistent formatting for feature/option names: follow existing project patterns for suffixes (e.g., prefer NCNN_SSE41 over NCNN_SSE4_1 to match conventions like NCNN_ARM82, NCNN_ARM86XXX). 3) Typo-proof build identifiers: for CMake, use the exact variable names (typos silently break behavior).

Example (CMake):

# Bad (typo)
set(CMAKE_EXECUTBLE_LINKER_FLAGS "${CMAKE_EXECUTBLE_LINKER_FLAGS} ...")

# Good
set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} -s FORCE_FILESYSTEM=1")

# Good option naming
option(NCNN_SSE41 "optimize ... with sse4.1 extension" ON)