* test(ghidra): require pending multi-HI16 coverage in the real MIPS relocatable lane
Post-merge review on #1950: the relocation oracle exposes coverage.multiple_hi16, but the real-Ghidra lane never required it, and Clang's C output never produces a LO16 that resolves several pending HI16s. Ghidra's loader could therefore mishandle that stream while the lane still passed, although most GCC-built kernel modules checked contain it.
The relocatable fixture adds an assembly block with two lui %hi(rea_mips_rel_carry); LLVM's relocation sort then leaves one HI16 pending until a later LO16 that resolves it together with another HI16, including the carry. The lane now requires multiple_hi16: false on the previous fixture, true for all three variants (LE, BE, soft-float module) on real Ghidra 12.1.4.
* test(ghidra): make the MIPS multi-HI16 fixture independent of relocation sorting
Review on #1974: the block used two %lo of rea_mips_rel_carry, a symbol with other %lo uses, so the relocation stream depended on the assembler's HI16/LO16 sort. Clang 21 happened to leave a HI16 pending; Clang 17 (per review) and GNU as 2.45 (checked here: HI@4 LO@8 HI@0 LO@10) pair each HI16 with its own LO16, so multiple_hi16 stays false and the lane fails.
Use a dedicated symbol with two %hi and exactly one %lo. Any assembler that orders each HI16 before a matching LO16 must then emit both HI16s ahead of that single LO16: Clang 21 gives HI@0 HI@4 LO@8, GNU as 2.45 gives HI@4 HI@0 LO@8. The real-Ghidra lane passes for LE, BE and the soft-float module variant with multiple_hi16 true.