refactor travis-ci:

osx does not come with gcc, actually it is clang. so, remove it.
move debhelper installation to "apt" plugin (it will affect only linux).
add otool (which is ldd equivalent) on osx.
split "before_install", "script" into matrix

.ci/before_install.sh

@@ -1,12 +0,0 @@
-#!/bin/bash
-set -eux
-
-if [[ "${TRAVIS_OS_NAME}" == "linux" ]]; then
-	sudo apt-get update
-	sudo apt-get -y install debhelper
-	bash .ci/build-openssl.sh > build-deps.log 2>&1 || (cat build-deps.log && exit 1)
-elif [[ "${TRAVIS_OS_NAME}" == "osx" ]]; then
-	brew update && brew upgrade openssl
-else
-	exit 1
-fi

.ci/script.sh

@@ -1,17 +0,0 @@
-#!/bin/bash
-set -eux
-
-if [[ "${TRAVIS_OS_NAME}" == "linux" ]]; then
-	export LD_LIBRARY_PATH="${HOME}/opt/lib:${LD_LIBRARY_PATH:-}"
-	export CFLAGS="-I${HOME}/opt/include"
-	export LDFLAGS="-L${HOME}/opt/lib"
-	./configure
-	make -C tmp
-	ldd bin/vpnserver/vpnserver
-	dh build-arch
-elif [[ "${TRAVIS_OS_NAME}" == "osx" ]]; then
-	./configure
-	make -C tmp
-else
-	exit 1
-fi

.travis.yml

@@ -20,10 +20,18 @@ matrix:
     - env: OPENSSL_VERSION="1.1.0f"
       os: linux
       compiler: clang
-    - os: osx
-      compiler: gcc
     - os: osx
       compiler: clang
+      before_install:
+        - brew update && brew upgrade openssl
+      script:
+        - ./configure
+        - make -C tmp
+        - otool -L bin/vpnserver/vpnserver
+
+addons:
+  apt:
+    packages: [ debhelper ]
 
 cache:
   directories:
@@ -31,7 +39,13 @@ cache:
   - ${HOME}/opt
 
 before_install:
-  - bash .ci/before_install.sh
+  - bash .ci/build-openssl.sh > build-deps.log 2>&1 || (cat build-deps.log && exit 1)
 
 script:
-  - bash .ci/script.sh
+  - export LD_LIBRARY_PATH="${HOME}/opt/lib:${LD_LIBRARY_PATH:-}"
+  - export CFLAGS="-I${HOME}/opt/include"
+  - export LDFLAGS="-L${HOME}/opt/lib"
+  - ./configure
+  - make -C tmp
+  - ldd bin/vpnserver/vpnserver
+  - dh build-arch