Stop setting $CARGO_HOME

cargo will use the user's $CARGO_HOME, or $HOME/.cargo by default.

Fixes bug 26497; bugfix on 0.3.1.5-alpha.

changes/bug26497

+  o Minor bugfixes (rust):
+    - Stop setting $CARGO_HOME. cargo will use the user's $CARGO_HOME, or
+      $HOME/.cargo by default. Fixes bug 26497; bugfix on 0.3.1.5-alpha.

src/rust/tor_util/include.am

@@ -7,7 +7,6 @@ EXTRA_DIST +=\
 src/rust/target/release/@TOR_RUST_UTIL_STATIC_NAME@: FORCE
 	( cd "$(abs_top_srcdir)/src/rust/tor_util" ; \
 		CARGO_TARGET_DIR="$(abs_top_builddir)/src/rust/target" \
-		CARGO_HOME="$(abs_top_builddir)/src/rust" \
 		$(CARGO) build --release --quiet $(CARGO_ONLINE) )
 
 FORCE:

src/test/test_rust.sh

@@ -9,7 +9,6 @@ for cargo_toml_dir in "${abs_top_srcdir:-../../..}"/src/rust/*; do
     if [ -e "${cargo_toml_dir}/Cargo.toml" ]; then
 	cd "${cargo_toml_dir}" && \
 	    CARGO_TARGET_DIR="${abs_top_builddir:-../../..}/src/rust/target" \
-	    CARGO_HOME="${abs_top_builddir:-../../..}/src/rust/.cargo" \
 	    "${CARGO:-cargo}" test ${CARGO_ONLINE-"--frozen"} \
 	    ${EXTRA_CARGO_OPTIONS} \
 	    --manifest-path "${cargo_toml_dir}/Cargo.toml" || exitcode=1