Updated travis to clang-9

.travis.yml

@@ -68,8 +68,13 @@ matrix:
 
       # Test clang-9.0: C++11, Build=Debug, ASAN=On
     - env: CLANG_VERSION=9 BUILD_TYPE=Debug CPP=11 ASAN=On TSAN=Off
-    # Test clang-9.0: C++11, Build=Release, ASAN=On
+      os: linux
+      addons: *clang90
+
+    # Test clang-9.0: C++11, Build=Release, ASAN=Off
     - env: CLANG_VERSION=9 BUILD_TYPE=Release CPP=11 ASAN=On TSAN=Off
+      os: linux
+      addons: *clang90
 
       
       # osx