Travis: build with both GCC and Clang

.travis.yml

@@ -2,10 +2,32 @@ language: rust
 
 matrix:
   include:
-    - env: TARGET=x86_64-unknown-linux-gnu
-      rust: nightly
+    - rust: nightly
+      env:
+      - MATRIX_EVAL="export CXX=g++-6"
+      - TARGET=x86_64-unknown-linux-gnu
+      addons:
+        apt:
+          sources:
+          - ubuntu-toolchain-r-test
+          packages:
+          - g++-6
 
-before_install: set -e
+    - rust: nightly
+      env:
+      - MATRIX_EVAL="export CXX=clang++-5.0"
+      - TARGET=x86_64-unknown-linux-gnu
+      addons:
+        apt:
+          sources:
+          - ubuntu-toolchain-r-test
+          - llvm-toolchain-trusty
+          packages:
+          - clang-5.0
+
+before_install:
+- set -e
+- eval "${MATRIX_EVAL}"
 
 script:
   - cargo check --target $TARGET
@@ -15,6 +37,10 @@ after_script: set +e
 
 cache: cargo
 
+branches:
+  only:
+  - master
+
 notifications:
   email:
-    on_success: never
+    on_success: never

appveyor.yml

@@ -39,5 +39,9 @@ notifications:
   - provider: Email
     on_build_success: false
 
+branches:
+  only:
+    - master
+
 # Building is done in the test phase, so we disable Appveyor's build phase.
 build: false

build.rs

@@ -8,6 +8,7 @@ fn main() {
         .flag("-pedantic")
         .flag("-Wall")
         .flag("-Werror")
+        .flag("-std=c++11")
         .flag("-D_GLIBCXX_USE_CXX11_ABI=0")
         .file("llvm/external-refs.cpp")
         .compile("librust-ptx-llvm-stuff.a");