[email protected] - Resolves memory overflow warnings

[cabelo]

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fix(repack): resolves memory overflow warnings and declaration error in make_block_*

• Fixes multiple warning: writing 32 bytes into a region of size 0 [-Wstringop-overflow=]
  in make_block_q4_0x4, make_block_q4_0x8, etc., caused by the use of memcpy in
  dynamically calculated offsets, which confuses static analysis in GCC 13+.

• Adds explicit bounds checking (if + GGML_ASSERT) before each memcpy,
  ensuring that src_offset and dst_offset do not exceed the sizes of the arrays
  (qs[]) within the blocks.

• Replaces memcpy directly with std::memcpy (C++) to avoid aliasing problems and
  improve compatibility with compiler optimizations. - Adds static_assert to validate block sizes (block_q4_0x4::qs == 64,

block_q4_Kx8::qs == 1024, etc.), preventing future errors if QK_* changes.

• Fixes compilation error make_block_q4_0x4 was not declared in this scope by declaring all auxiliary functions make_block_* as static at the top of the repack.cpp file, before extern "C", following good C++ practices (internal binding).

• No changes to algorithm logic — only memory safety and compatibility with modern compilers (GCC ≥13, Clang ≥14).

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After