[MXNET-855] Update clang to version 6

Jenkinsfile

@@ -173,12 +173,12 @@ core_logic: {
         }
       }
     },
-    'CPU: Clang 5': {
+    'CPU: Clang 6': {
       node(NODE_LINUX_CPU) {
-        ws('workspace/build-cpu-clang50') {
+        ws('workspace/build-cpu-clang60') {
           timeout(time: max_time, unit: 'MINUTES') {
             utils.init_git()
-            utils.docker_run('ubuntu_cpu', 'build_ubuntu_cpu_clang50', false)
+            utils.docker_run('ubuntu_cpu', 'build_ubuntu_cpu_clang60', false)
           }
         }
       }
@@ -194,13 +194,13 @@ core_logic: {
         }
       }
     },
-    'CPU: Clang 5 MKLDNN': {
+    'CPU: Clang 6 MKLDNN': {
       node(NODE_LINUX_CPU) {
-        ws('workspace/build-cpu-mkldnn-clang50') {
+        ws('workspace/build-cpu-mkldnn-clang60') {
           timeout(time: max_time, unit: 'MINUTES') {
             utils.init_git()
-            utils.docker_run('ubuntu_cpu', 'build_ubuntu_cpu_clang50_mkldnn', false)
-            utils.pack_lib('mkldnn_cpu_clang5', mx_mkldnn_lib)
+            utils.docker_run('ubuntu_cpu', 'build_ubuntu_cpu_clang60_mkldnn', false)
+            utils.pack_lib('mkldnn_cpu_clang6', mx_mkldnn_lib)
           }
         }
       }

ci/docker/install/ubuntu_clang.sh

@@ -21,11 +21,11 @@
 # the whole docker cache for the image
 
 set -ex
-# Install clang 3.9 (the same version as in XCode 8.*) and 5.0 (latest major release)
+# Install clang 3.9 (the same version as in XCode 8.*) and 6.0 (latest major release)
 wget -O - http://apt.llvm.org/llvm-snapshot.gpg.key | apt-key add - && \
     apt-add-repository "deb http://apt.llvm.org/xenial/ llvm-toolchain-xenial-3.9 main" && \
-    apt-add-repository "deb http://apt.llvm.org/xenial/ llvm-toolchain-xenial-5.0 main" && \
+    apt-add-repository "deb http://apt.llvm.org/xenial/ llvm-toolchain-xenial-6.0 main" && \
     apt-get update && \
-    apt-get install -y clang-3.9 clang-5.0 && \
+    apt-get install -y clang-3.9 clang-6.0 && \
     clang-3.9 --version && \
-    clang-5.0 --version
+    clang-6.0 --version

ci/docker/runtime_functions.sh

@@ -349,11 +349,11 @@ build_ubuntu_cpu_clang39() {
         -j$(nproc)
 }
 
-build_ubuntu_cpu_clang50() {
+build_ubuntu_cpu_clang60() {
     set -ex
 
-    export CXX=clang++-5.0
-    export CC=clang-5.0
+    export CXX=clang++-6.0
+    export CC=clang-6.0
 
     build_ccache_wrappers
 
@@ -381,11 +381,11 @@ build_ubuntu_cpu_clang39_mkldnn() {
         -j$(nproc)
 }
 
-build_ubuntu_cpu_clang50_mkldnn() {
+build_ubuntu_cpu_clang60_mkldnn() {
     set -ex
 
-    export CXX=clang++-5.0
-    export CC=clang-5.0
+    export CXX=clang++-6.0
+    export CC=clang-6.0
 
     build_ccache_wrappers