Remove travis configs that are covered by actions (#1145)

.travis.yml

@@ -11,10 +11,6 @@ matrix:
             - lcov
       env: COMPILER=g++ C_COMPILER=gcc BUILD_TYPE=Coverage
     - compiler: gcc
-      env: COMPILER=g++ C_COMPILER=gcc BUILD_TYPE=Debug
-    - compiler: gcc
-      env: COMPILER=g++ C_COMPILER=gcc BUILD_TYPE=Release
-    - compiler: gcc
       addons:
         apt:
           packages:
@@ -44,10 +40,6 @@ matrix:
         - COMPILER=g++-6 C_COMPILER=gcc-6  BUILD_TYPE=Debug
         - ENABLE_SANITIZER=1
         - EXTRA_FLAGS="-fno-omit-frame-pointer -g -O2 -fsanitize=undefined,address -fuse-ld=gold"
-    - compiler: clang
-      env: COMPILER=clang++ C_COMPILER=clang BUILD_TYPE=Debug
-    - compiler: clang
-      env: COMPILER=clang++ C_COMPILER=clang BUILD_TYPE=Release
     # Clang w/ libc++
     - compiler: clang
       dist: xenial
@@ -150,25 +142,10 @@ matrix:
       osx_image: xcode8.3
       compiler: clang
       env:
-        - COMPILER=clang++ BUILD_TYPE=Debug
-    - os: osx
-      osx_image: xcode8.3
-      compiler: clang
-      env:
-        - COMPILER=clang++ BUILD_TYPE=Release
-    - os: osx
-      osx_image: xcode8.3
-      compiler: clang
-      env:
         - COMPILER=clang++
         - BUILD_TYPE=Release
         - BUILD_32_BITS=ON
         - EXTRA_FLAGS="-m32"
-    - os: osx
-      osx_image: xcode9.4
-      compiler: gcc
-      env:
-        - COMPILER=g++-7 C_COMPILER=gcc-7  BUILD_TYPE=Debug
 
 before_script:
   - if [ -n "${LIBCXX_BUILD}" ]; then