opt: use cross to build armv7

Cross.toml

@@ -0,0 +1,21 @@
+[build]
+build-std = false                              # do not build the std library. has precedence over xargo
+xargo = true                                   # enable the use of xargo by default
+# zig = false                                    # do not use zig cc for the builds
+default-target = "x86_64-unknown-linux-gnu"    # use this target if none is explicitly provided
+
+[build.env]
+volumes = ["VCPKG_ROOT"] # "VOL2_ARG=/path/to/volume"
+passthrough = ["VCPKG_ROOT"]
+
+[target.aarch64-unknown-linux-gnu]
+# pre-build = ["env ARCH=arm64 ./res/install-rust-deps.sh"]
+# build-std = false          # always build the std library. has precedence over xargo
+# xargo = false              # disable the use of xargo
+# image = "test-image"       # use a different image for the target
+# runner = "qemu-user"       # wrapper to run the binary (must be `qemu-system`, `qemu-user`, or `native`).
+
+[target.arm-unknown-linux-gnueabihf]
+pre-build = "./res/install-rust-deps-arm.sh"
+# volumes = ["VCPKG_ROOT"] # "VOL2_ARG=/path/to/volume"
+# passthrough = ["VCPKG_ROOT"]