Exclude low importance entries from large build matrix

Anything that causes those entries to fail would probably cause other
entries (similar env/php version) to also fail.

.travis.yml

@@ -24,16 +24,6 @@ env:
   # The VM implementation is different on 32-bit php. Test those as well.
   - CC=gcc-4.8 CXX=g++-4.8 USE_32BIT=1 VALGRIND=1 PHP_NTS_USE=actually-zts PHP_CONFIGURE_ARGS='--disable-all --enable-maintainer-zts --enable-debug --enable-session'
 
-install:
-  - sudo apt-get install -qq $CC
-  - $CC --version
-  - if [ "x$USE_32BIT" != "x" ]; then sudo apt-get install -y g++-4.8-multilib libc6-dev-i386; export CC="$PWD/ci/gcc-32.sh"; export CXX="$PWD/ci/g++-32.sh"; $CC --version;  fi
-  # Test some builds with valgrind to check for memory leaks and invalid memory accesses
-  - if [ "$VALGRIND" -eq 1 ]; then sudo apt-get install -qq valgrind; export TEST_PHP_ARGS="-m"; valgrind --version; fi
-  # For NTS builds: Install NTS and set the php.ini to a different blank file.
-  - if [ "x$PHP_NTS_USE" != "x" ]; then export PHP_NTS_VERSION=$(./ci/get_global_php_version.sh); echo "Version is $PHP_NTS_VERSION"; ./ci/install_php_nts.sh || exit 1; export PATH="$(./ci/generate_php_install_dir.sh)/bin:$PATH"; export PHPRC=$PWD/ci/; else ./ci/wipe_travis_cache.sh; fi
-  - if [ "$VALGRIND" -eq 1 -a "x$USE_32BIT" != "x" ]; then sudo apt-get install -y libc6-dbg:i386; fi
-
 # Defined at https://github.com/php-build/php-build/tree/master/share/php-build/definitions
 php:
   - master
@@ -44,6 +34,25 @@ php:
 matrix:
   allow_failures:
     - php: master
+  exclude:
+    - php: 7.0
+      env: CC=gcc-4.8 CXX=g++-4.8
+    - php: master
+      env: CC=gcc-4.8 CXX=g++-4.8
+    - php: master
+      env: CC=gcc-4.8 CXX=g++-4.8 VALGRIND=1 PHP_NTS_USE=1 PHP_CONFIGURE_ARGS='--disable-all --disable-zts --enable-debug --enable-session'
+    - php: master
+      env: CC=clang
+
+install:
+  - sudo apt-get install -qq $CC
+  - $CC --version
+  - if [ "x$USE_32BIT" != "x" ]; then sudo apt-get install -y g++-4.8-multilib libc6-dev-i386; export CC="$PWD/ci/gcc-32.sh"; export CXX="$PWD/ci/g++-32.sh"; $CC --version;  fi
+  # Test some builds with valgrind to check for memory leaks and invalid memory accesses
+  - if [ "$VALGRIND" -eq 1 ]; then sudo apt-get install -qq valgrind; export TEST_PHP_ARGS="-m"; valgrind --version; fi
+  # For NTS builds: Install NTS and set the php.ini to a different blank file.
+  - if [ "x$PHP_NTS_USE" != "x" ]; then export PHP_NTS_VERSION=$(./ci/get_global_php_version.sh); echo "Version is $PHP_NTS_VERSION"; ./ci/install_php_nts.sh || exit 1; export PATH="$(./ci/generate_php_install_dir.sh)/bin:$PATH"; export PHPRC=$PWD/ci/; else ./ci/wipe_travis_cache.sh; fi
+  - if [ "$VALGRIND" -eq 1 -a "x$USE_32BIT" != "x" ]; then sudo apt-get install -y libc6-dbg:i386; fi
 
 before_script:
  - $CC --version && ci/print_php_int_max.php