Fix target C++ MX overload EffectiveM/EffectiveN compile closure

[zhoubot]

Problem

With LLVM frontend PR LinxISA/llvm-project#69 providing the previously missing linx_blkc.h, tile_size, Tr/Sr/vr, and a built 0.58.3 libc++ sysroot, merged TileOP 2e4d6959 reaches a TileOP-owned compile error:

• include/jcore/template_asm.hpp:4656,4667,4672,4704,4705
• EffectiveN / EffectiveM are undeclared in the affected MX overloads.

Both test/tileop_api/compile.all and the fail-closed negative preflight reach the same error. This was previously masked by the missing compiler frontend package.

Required closure

• Define/thread effective non-transposed/transposed M/N/K values correctly for all affected zero/A-only/B-only/both-scale TMATMUL/TGEMV variants.
• Add target C++ positive compilation coverage, not only host syntax/text checks.
• Rerun compile.all, run_negatives.sh, and exact MC/disassembly using the 0.58.3 musl+libc++ sysroot and LLVM fix: row-reduction B.DIM describes the source tile geometry #69 build.

Tracked by LinxISA/linx-isa#180.