Forward CMake configs to Cargo

cmake/Rust.cmake

@@ -67,6 +67,10 @@ corrosion_set_env_vars(${fish_rust_target}
     "PREFIX=${CMAKE_INSTALL_PREFIX}"
     # Temporary hack to propogate CMake flags/options to build.rs.
     "CMAKE_WITH_GETTEXT=${CMAKE_WITH_GETTEXT}"
+    "DOCDIR=${DOCDIR}"
+    "DATADIR=${DATADIR}"
+    "SYSCONFDIR=${SYSCONFDIR}"
+    "BINDIR=${BINDIR}"
 )
 
 # this needs an extra fish-rust due to the poor source placement