build: Place target in meson build dir

Instead of putting target/ and target_test/ in the source
directory, we can tell our cargo script to put both target
and our cargo-home in meson's build directory.

In addition, makes tests and builds use the same target
directory, significantly reducing the time it takes to run tests.

scripts/cargo.sh

@@ -2,11 +2,10 @@
 
 set -ex
 
-export CARGO_HOME=$1/target/cargo-home
-export LOCALEDIR="$3"
-export APP_ID="$4"
-export VERSION="$5"
-export PROFILE="$6"
+export OUTPUT="$2"
+export CARGO_TARGET_DIR="$3"/target
+export CARGO_HOME="$CARGO_TARGET_DIR"/cargo-home
+export PROFILE="$4"
 
 TARGET=debug
 ARGS=()
@@ -23,4 +22,4 @@ if test -d vendor; then
 fi
 
 cargo build ${ARGS[@]} --manifest-path="$1"/Cargo.toml -p podcasts-gtk &&
-cp $1/target/${TARGET}/podcasts-gtk $2
+cp "$CARGO_TARGET_DIR"/${TARGET}/podcasts-gtk "$OUTPUT"

scripts/test.sh

@@ -1,10 +1,9 @@
 #! /usr/bin/sh
 
 set -o errexit
-set -o nounset
 set -o pipefail
 
-export CARGO_HOME="target/cargo-home"
-export CARGO_TARGET_DIR="target_test/"
+export CARGO_TARGET_DIR="$1/target/"
+export CARGO_HOME="$CARGO_TARGET_DIR/cargo-home"
 
 cargo test -j 1 -- --test-threads=1 --nocapture