Do not use vendored code on aarch64

Author: jeroen

src/Makevars.ucrt

@@ -8,7 +8,10 @@ all: clean rustup
 $(SHLIB): $(STATLIB)
 
 $(STATLIB):
+ifeq ($(TARGET),x86_64-pc-windows-gnu)
+	@echo Building for $(TARGET) from vendor.tar.xz sources!
 	if [ -f myrustlib/vendor.tar.xz ]; then tar xf myrustlib/vendor.tar.xz && mkdir -p .cargo && cp myrustlib/vendor-config.toml .cargo/config.toml; fi
+endif
 	PATH="$(USERPROFILE)\\.cargo\\bin:$(PATH)" cargo build --target=$(TARGET) --release --manifest-path=myrustlib/Cargo.toml
 	rm -Rf $(LIBDIR)/build