ci: more attempts at open SSL support

.travis.yml

@@ -1,9 +1,26 @@
 language: rust
-env: OPENSSL=1.1.0
+sudo: required
+dist: trusty
+
+cache:
+  cargo: true
+
+env:
+  global:
+    - OPENSSL_VERSION=openssl-1.0.2
+
+
+before_install:
+  - sudo add-apt-repository -y ppa:0k53d-karl-f830m/openssl
+  - sudo apt-get update -qq
+  - sudo apt-get install -y openssl libssl-dev libelf-dev libdw-dev cmake gcc binutils-dev libiberty-dev
+
 rust:
   - stable
+
 before_script:
-  - rustup component add rustfmt-preview
+  - export PATH=$PATH:~/.cargo/bin
+
 script:
   - cargo build
   - cargo test