travis: install linker

.travis.yml

@@ -4,19 +4,47 @@ matrix:
   include:
     - env: TARGET=x86_64-unknown-linux-gnu
       rust: nightly
+
     - env: TARGET=thumbv6m-none-eabi
       rust: nightly
+      addons:
+        apt:
+          sources:
+            - debian-sid
+          packages:
+            - binutils-arm-none-eabi
+
     - env: TARGET=thumbv7m-none-eabi
       rust: nightly
+      addons:
+        apt:
+          sources:
+            - debian-sid
+          packages:
+            - binutils-arm-none-eabi
+
     - env: TARGET=thumbv7em-none-eabi
       rust: nightly
+      addons:
+        apt:
+          sources:
+            - debian-sid
+          packages:
+            - binutils-arm-none-eabi
+
     - env: TARGET=thumbv7em-none-eabihf
       rust: nightly
+      addons:
+        apt:
+          sources:
+            - debian-sid
+          packages:
+            - binutils-arm-none-eabi
 
 before_install: set -e
 
 install:
-  - sh ci/install.sh
+  - bash ci/install.sh
 
 script:
   - bash ci/script.sh

ci/install.sh

-set -ex
+set -euxo pipefail
 
 main() {
     case $TARGET in

ci/script.sh

-set -ex
+set -euxo pipefail
 
 main() {
     if [ $TARGET = x86_64-unknown-linux-gnu ]; then