use libstdc++ 4.8, which avoids the need for a special ppa

Author: kripken

.travis.yml

@@ -1,4 +1,5 @@
 sudo: false
+dist: trusty
 language: cpp
 python:
   - "2.7"
@@ -8,26 +9,22 @@ matrix:
 
     - env: CC_COMPILER="./test/wasm-install/wasm-install/bin/clang" CXX_COMPILER="./test/wasm-install/wasm-install/bin/clang++"
       compiler: clang
-      addons: &gcc5
+      addons: &stuff
         apt:
           sources: ['ubuntu-toolchain-r-test']
-          packages: ['cmake', 'nodejs', 'g++-5']
+          packages: ['cmake', 'nodejs', 'libstdc++-4.8-dev']
 
     - env: CC_COMPILER="./test/wasm-install/wasm-install/bin/clang" CXX_COMPILER="./test/wasm-install/wasm-install/bin/clang++" COMPILER_FLAGS="-fsanitize=undefined -fno-sanitize-recover=all -fsanitize-blacklist=`pwd`/ubsan.blacklist"
       compiler: clang
-      addons: *gcc5
+      addons: *stuff
 
     - env: CC_COMPILER="./test/wasm-install/wasm-install/bin/clang" CXX_COMPILER="./test/wasm-install/wasm-install/bin/clang++" COMPILER_FLAGS="-fsanitize=address"
       compiler: clang
-      addons: *gcc5
+      addons: *stuff
 
     - env: CC_COMPILER="./test/wasm-install/wasm-install/bin/clang" CXX_COMPILER="./test/wasm-install/wasm-install/bin/clang++" COMPILER_FLAGS="-fsanitize=thread"
       compiler: clang
-      addons: *gcc5
-
-    - env: CC_COMPILER="gcc-5" CXX_COMPILER="g++-5"
-      compiler: gcc
-      addons: *gcc5
+      addons: *stuff
 
 before_install:
   - export CC="${CC_COMPILER}"

CMakeLists.txt

@@ -63,6 +63,7 @@ ELSE()
   ADD_COMPILE_FLAG("-Werror")
   ADD_COMPILE_FLAG("-Wextra")
   ADD_COMPILE_FLAG("-Wno-unused-parameter")
+  ADD_COMPILE_FLAG("-Wno-mismatched-tags") # libstdc++4.8 issue on trusty
   ADD_COMPILE_FLAG("-fno-omit-frame-pointer")
   ADD_COMPILE_FLAG("-fPIC")
   IF(uppercase_CMAKE_BUILD_TYPE STREQUAL "DEBUG")