[LA64_DYNAREC] Fixed emit_add16 LBT implementation (#1875) #4155

Job	Run time
build (X64, Release, ubuntu-latest)	1m 37s
build (X64, Trace, ubuntu-latest)	1m 53s
build (X64, Box32, ubuntu-latest)	1m 35s
build (RISCV, Release, ubuntu-latest)	5m 36s
build (RISCV, Trace, ubuntu-latest)	6m 13s
build (RISCV, StaticBuild, ubuntu-latest)	4m 10s
build (RISCV, Box32, ubuntu-latest)	5m 50s
build (RK3588, Release, ubuntu-latest)	5m 20s
build (RK3588, Trace, ubuntu-latest)	5m 30s
build (RK3588, StaticBuild, ubuntu-latest)	3m 45s
build (RK3588, Box32, ubuntu-latest)	5m 26s
build (ARM64, Release, ubuntu-latest)	5m 10s
build (ARM64, Trace, ubuntu-latest)	6m 5s
build (ARM64, StaticBuild, ubuntu-latest)	3m 43s
build (ARM64, Box32, ubuntu-latest)	5m 30s
build (ANDROID, Release, ubuntu-latest)	2m 8s
build (ANDROID, Trace, ubuntu-latest)	2m 30s
build (TERMUX, Release, ubuntu-latest)	2m 5s
build (TERMUX, Trace, ubuntu-latest)	2m 17s
build (LARCH64, Release, ubuntu-latest)	3m 21s
build (LARCH64, Trace, ubuntu-latest)	3m 38s
build (LARCH64, StaticBuild, ubuntu-latest)	1m 55s
build (LARCH64, Box32, ubuntu-latest)	3m 32s
	1h 28m 49s

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