Update Dockerfile and README to not use syntex anymore

README.md

@@ -73,9 +73,9 @@ docker run -v /tmp/librespot-build:/build librespot-cross
 
 If only one architecture is desired, cargo can be invoked directly with the appropriate options :
 ```shell
-docker run -v /tmp/librespot-build:/build librespot-cross cargo build --release --no-default-features --features "with-syntex alsa-backend"
-docker run -v /tmp/librespot-build:/build librespot-cross cargo build --release --target arm-unknown-linux-gnueabihf --no-default-features --features "with-syntex alsa-backend"
-docker run -v /tmp/librespot-build:/build librespot-cross cargo build --release --target arm-unknown-linux-gnueabi --no-default-features --features "with-syntex alsa-backend"
+docker run -v /tmp/librespot-build:/build librespot-cross cargo build --release --no-default-features --features alsa-backend
+docker run -v /tmp/librespot-build:/build librespot-cross cargo build --release --target arm-unknown-linux-gnueabihf --no-default-features --features alsa-backend
+docker run -v /tmp/librespot-build:/build librespot-cross cargo build --release --target arm-unknown-linux-gnueabi --no-default-features --features alsa-backend
 ```
 
 ## Development

contrib/Dockerfile

@@ -8,9 +8,9 @@
 # The compiled binaries will be located in /tmp/librespot-build
 #
 # If only one architecture is desired, cargo can be invoked directly with the appropriate options :
-# $ docker run -v /tmp/librespot-build:/build librespot-cross cargo build --release --no-default-features --features "with-syntex alsa-backend"
-# $ docker run -v /tmp/librespot-build:/build librespot-cross cargo build --release --target arm-unknown-linux-gnueabihf --no-default-features --features "with-syntex alsa-backend"
-# $ docker run -v /tmp/librespot-build:/build librespot-cross cargo build --release --target arm-unknown-linux-gnueabi --no-default-features --features "with-syntex alsa-backend"
+# $ docker run -v /tmp/librespot-build:/build librespot-cross cargo build --release --no-default-features --features "alsa-backend"
+# $ docker run -v /tmp/librespot-build:/build librespot-cross cargo build --release --target arm-unknown-linux-gnueabihf --no-default-features --features "alsa-backend"
+# $ docker run -v /tmp/librespot-build:/build librespot-cross cargo build --release --target arm-unknown-linux-gnueabi --no-default-features --features "alsa-backend"
 #
 
 FROM debian:stretch

contrib/docker-build.sh

@@ -1,6 +1,6 @@
 #!/usr/bin/env bash
 set -eux
 
-cargo build --release --no-default-features --features "with-syntex alsa-backend"
-cargo build --release --target arm-unknown-linux-gnueabihf --no-default-features --features "with-syntex alsa-backend"
-cargo build --release --target arm-unknown-linux-gnueabi --no-default-features --features "with-syntex alsa-backend"
+cargo build --release --no-default-features --features alsa-backend
+cargo build --release --target arm-unknown-linux-gnueabihf --no-default-features --features alsa-backend
+cargo build --release --target arm-unknown-linux-gnueabi --no-default-features --features alsa-backend