Try to add qemu for travis

.travis.yml

@@ -3,13 +3,19 @@ language: rust
 rust:
     - nightly
 
-cache: cargo
+cache: 
+  - cargo
+  directories:
+    - $HOME/qemu
 
 before_script:
   - rustup component add rust-src
   - (test -x $HOME/.cargo/bin/cargo-install-update || cargo install cargo-update)
   - (test -x $HOME/.cargo/bin/xargo || cargo install xargo)
   - cargo install-update -a
+  # setup qemu
+  - bash -e travis-qemu.sh
+  - export PATH=$PATH:$HOME/qemu/bin
 
 sudo: false
 

travis-qemu.sh

@@ -0,0 +1,39 @@
+#!/bin/bash
+set -e
+
+VERSION=${QEMU_VERSION:=2.11.1}
+ARCHES=${QEMU_ARCHES:=arm aarch64 i386 x86_64}
+TARGETS=${QEMU_TARGETS:=$(echo $ARCHES | sed 's#$# #;s#\([^ ]*\) #\1-softmmu \1-linux-user #g')}
+
+if echo "$VERSION $TARGETS" | cmp --silent $HOME/qemu/.build -; then
+  echo "qemu $VERSION up to date!"
+  exit 0
+fi
+
+echo "VERSION: $VERSION"
+echo "TARGETS: $TARGETS"
+
+cd $HOME
+rm -rf qemu
+
+# Checking for a tarball before downloading makes testing easier :-)
+test -f "qemu-$VERSION.tar.bz2" || wget "http://wiki.qemu-project.org/download/qemu-$VERSION.tar.bz2"
+tar -xf "qemu-$VERSION.tar.bz2"
+cd "qemu-$VERSION"
+
+./configure \
+  --prefix="$HOME/qemu" \
+  --target-list="$TARGETS" \
+  --disable-docs \
+  --disable-sdl \
+  --disable-gtk \
+  --disable-gnutls \
+  --disable-gcrypt \
+  --disable-nettle \
+  --disable-curses \
+  --static
+
+make -j4
+make install
+
+echo "$VERSION $TARGETS" > $HOME/qemu/.build