Add hematite

recipes/hematite/recipe.sh

+GIT=https://gitlab.redox-os.org/redox-os/hematite.git
+GIT_UPSTREAM=https://github.com/PistonDevelopers/hematite.git
+BUILD_DEPENDS=(mesa)
+BRANCH=redox
+
+function recipe_build {
+    sysroot="$(realpath ../sysroot)"
+    cp -p "$ROOT/Xargo.toml" "Xargo.toml"
+    xargo rustc --target "$TARGET" --release ${CARGOFLAGS} \
+        -- \
+        -L "${sysroot}/lib" \
+        -l OSMesa \
+        -l glapi \
+        -l stdc++ \
+        -C link-args="-Wl,--whole-archive -lpthread -Wl,--no-whole-archive"
+    skip=1
+}