try build matrix in .travis.yml

.travis.yml

 language: cpp
 
+compiler:
+- clang
+- gcc
+
+env:
+- PURPOSE=compile
+- PURPOSE=unittest
+
 sudo: required
 
 install:
-    - sudo apt-get install -qq realpath libgflags-dev libprotobuf-dev libprotoc-dev protobuf-compiler libleveldb-dev libgoogle-perftools-dev
-    - sudo apt-get install libgtest-dev && cd /usr/src/gtest && sudo cmake . && sudo make && sudo mv libgtest* /usr/lib/ && cd -
-    - sh config_brpc.sh --headers=/usr/include --libs=/usr/lib --nodebugsymbols
-    - make -j4
+- sudo apt-get install -qq realpath libgflags-dev libprotobuf-dev libprotoc-dev protobuf-compiler libleveldb-dev libgoogle-perftools-dev
+- sudo apt-get install libgtest-dev && cd /usr/src/gtest && sudo cmake . && sudo make && sudo mv libgtest* /usr/lib/ && cd -
 
 script:
-    - cd test && sh ./run_tests.sh
+- sh build_in_travis_ci.sh

build_in_travis_ci.sh

+if [ -z "$PURPOSE" ]; then
+    echo "PURPOSE must be set"
+    exit 1
+fi
+if [ -z "$CXX" ]; then
+    echo "CXX must be set"
+    exit 1
+fi
+if [ -z "$CC" ]; then
+    echo "CC must be set"
+    exit 1
+fi
+echo "build combination: PURPOSE=$PURPOSE CXX=$CXX CC=$CC"
+# The default env in travis-ci is Ubuntu.
+if ! sh config_brpc.sh --headers=/usr/include --libs=/usr/lib --nodebugsymbols --cxx=$CXX --cc=$CC; then
+    echo "Fail to configure brpc"
+    exit 1
+fi
+if [ "$PURPOSE" = "compile" ]; then
+    make -j4
+elif [ "$PURPOSE" = "unittest" ]; then
+    cd test && sh ./run_tests.sh
+else
+    echo "Unknown purpose=\"$PURPOSE\""
+fi