build: add rust target for macOS cross compiles

When we build the macOS pkg, we build Node.js twice (on arm64):
- Once for arm64 (native)
- Once for x64, using a combination of Rosetta 2 and compiler flags

before combining both into a universal binary.

For the x64 case, pass target flag to `rustc` so that the binary is
built for the correct target architecture.

Signed-off-by: Richard Lau <[email protected]>

Author: richardlau

Makefile

@@ -1182,7 +1182,8 @@ endif
 		--tag=$(TAG) \
 		--release-urlbase=$(RELEASE_URLBASE) \
 		$(CONFIG_FLAGS) $(BUILD_RELEASE_FLAGS)
-	arch -x86_64 $(MAKE) install V=$(V) DESTDIR=$(MACOSOUTDIR)/dist/x64/node
+	CARGO_BUILD_TARGET="x86_64-apple-darwin" \
+		arch -x86_64 $(MAKE) install V=$(V) DESTDIR=$(MACOSOUTDIR)/dist/x64/node
 	SIGN="$(CODESIGN_CERT)" PKGDIR="$(MACOSOUTDIR)/dist/x64/node/usr/local" sh \
 		tools/osx-codesign.sh
 	$(PYTHON) ./configure \