Building on Linux requires alsa

[gsurrel]

It seems that building that image viewer requires an audio library (Alsa):

cargo run --release       

error: failed to run custom build command for `alsa-sys v0.3.1`

Caused by:
  process didn't exit successfully: `/tmp/img_maniac/target/release/build/alsa-sys-6f16022a8ae0a3fc/build-script-build` (exit status: 101)
  --- stdout
  cargo:rerun-if-env-changed=ALSA_NO_PKG_CONFIG
  cargo:rerun-if-env-changed=PKG_CONFIG_x86_64-unknown-linux-gnu
  cargo:rerun-if-env-changed=PKG_CONFIG_x86_64_unknown_linux_gnu
  cargo:rerun-if-env-changed=HOST_PKG_CONFIG
  cargo:rerun-if-env-changed=PKG_CONFIG
  cargo:rerun-if-env-changed=ALSA_STATIC
  cargo:rerun-if-env-changed=ALSA_DYNAMIC
  cargo:rerun-if-env-changed=PKG_CONFIG_ALL_STATIC
  cargo:rerun-if-env-changed=PKG_CONFIG_ALL_DYNAMIC
  cargo:rerun-if-env-changed=PKG_CONFIG_PATH_x86_64-unknown-linux-gnu
  cargo:rerun-if-env-changed=PKG_CONFIG_PATH_x86_64_unknown_linux_gnu
  cargo:rerun-if-env-changed=HOST_PKG_CONFIG_PATH
  cargo:rerun-if-env-changed=PKG_CONFIG_PATH
  cargo:rerun-if-env-changed=PKG_CONFIG_LIBDIR_x86_64-unknown-linux-gnu
  cargo:rerun-if-env-changed=PKG_CONFIG_LIBDIR_x86_64_unknown_linux_gnu
  cargo:rerun-if-env-changed=HOST_PKG_CONFIG_LIBDIR
  cargo:rerun-if-env-changed=PKG_CONFIG_LIBDIR
  cargo:rerun-if-env-changed=PKG_CONFIG_SYSROOT_DIR_x86_64-unknown-linux-gnu
  cargo:rerun-if-env-changed=PKG_CONFIG_SYSROOT_DIR_x86_64_unknown_linux_gnu
  cargo:rerun-if-env-changed=HOST_PKG_CONFIG_SYSROOT_DIR
  cargo:rerun-if-env-changed=PKG_CONFIG_SYSROOT_DIR

  --- stderr
  thread 'main' panicked at '`PKG_CONFIG_ALLOW_SYSTEM_CFLAGS="1" PKG_CONFIG_ALLOW_SYSTEM_LIBS="1" "pkg-config" "--libs" "--cflags" "alsa"` did not exit successfully: exit status: 1
  error: could not find system library 'alsa' required by the 'alsa-sys' crate

  --- stderr
  Package alsa was not found in the pkg-config search path.
  Perhaps you should add the directory containing `alsa.pc'
  to the PKG_CONFIG_PATH environment variable
  No package 'alsa' found
  ', /home/gsurrel/.cargo/registry/src/github.com-1ecc6299db9ec823/alsa-sys-0.3.1/build.rs:13:18
  note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

Maybe it's possible to opt-out easily?

[AllenDang]

audio should be removed now