test: pass the drop-motion and install.sh signature tests on Apple silicon

Vanilla's Math.sin is HotSpot's intrinsic, which rounds one of the drop
test's throws a bit lower on AArch64 than on x86-64; a vanilla 26.3 run
on an M-series Mac gives the AArch64 value. The install.sh fixture only
holds the Linux x86-64 archive and ran the cases with /usr/bin's
OpenSSL, LibreSSL on macOS: a fake uname picks that archive, and the
cases get the OpenSSL 3 the script checked for.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

crates/horizon-client/src/entities.rs

@@ -120,7 +120,13 @@ mod drop_motion_tests {
                 [
                     -4627867408251048793,
                     4597245257657090048,
-                    4597448471913462163,
+                    // Vanilla's `Math.sin` is HotSpot's intrinsic, which rounds this
+                    // one a bit lower on AArch64 than on x86-64 (`jmath`).
+                    if cfg!(target_arch = "aarch64") {
+                        4597448471913462162
+                    } else {
+                        4597448471913462163
+                    },
                 ],
             ),
             (

tests/install_sh_signature.sh

@@ -67,6 +67,12 @@ esac
 if [ -n "$out" ]; then cp "$src" "$out"; else cat "$src"; fi
 CURL
 chmod +x "$W/fake/curl"
+# The fake uname: install.sh picks the Linux x86-64 archive, the one these releases hold, on any machine.
+cat > "$W/fake/uname" <<'UNAME'
+#!/bin/sh
+case "$1" in -m) echo x86_64 ;; *) echo Linux ;; esac
+UNAME
+chmod +x "$W/fake/uname"
 
 # install.sh with the throwaway public key in place of the release key.
 with_key() {  # dir -> prints path of the patched copy
@@ -86,7 +92,9 @@ edit() {  # sed-expression file
   sed "$1" "$2" > "$2.tmp" && mv "$2.tmp" "$2"
 }
 mkdir -p "$W/home"
-P=/usr/bin:/bin
+# The cases get the OpenSSL 3 checked above, wherever it is: macOS's /usr/bin has LibreSSL.
+mkdir "$W/ssl"; ln -s "$(command -v openssl)" "$W/ssl/openssl"
+P=$W/ssl:/usr/bin:/bin
 
 # 1. Good signature, a Nightly: SHA256SUMS.v2.sig signed for the version its title names.
 NIGHTLY=nightly-2026-11-03-0c02067