feat(asm): the immediate multiply and arm64 indirect branches GOROOT writes

Assisted-by: GLM 5.3 Flash

CHANGELOG.md

@@ -19,12 +19,16 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   access pair assembles as the toolchain's one-instruction form (the
   bare `MOVQ TLS, r` load nops out and `off(r)(TLS*1)` folds to the
   segment-prefixed absolute whose disp32 carries the R_TLSLE
-  relocation, per-GOOS); and `gasm asm` predefines the `GOARCH_<arch>`
+  relocation, per-GOOS); arm64 accepts the bare-register indirect branch
+  (`BL R9` beside `BL (R9)`, both BLR) and the zero-immediate store
+  (`MOVD $0, mem` through the zero register, rejecting non-zero immediates
+  as the toolchain does); and `gasm asm` predefines the `GOARCH_<arch>`
   and `GOOS_<goos>` macros the go command passes to `go tool asm`, so
   GOROOT headers' `#ifdef GOARCH_amd64` platform blocks (`go_tls.h`'s
   `get_tls` and friends) select as intended.  The GOROOT corpus measure
-  moves to 267 of 353 files assembling for every target architecture
-  (75.6 %), 89.4 % of the real-code corpus, from 70.8 % and 82.2 %.
+  moves to 276 of 353 files assembling for every target architecture
+  (78.2 %), 91.4 % of the real-code corpus (280 of 303), from 70.8 %
+  and 82.2 %.
 
 ### Added