try to fix clang build (use libc++)

.travis.yml

@@ -10,7 +10,7 @@ before_install:
   - if [ "$TRAVIS_OS_NAME" == "linux" ]; then tar -xzvf cmake-3.2.3-Linux-x86_64.tar.gz; fi
   - if [ "$TRAVIS_OS_NAME" == "linux" ]; then export PATH=$PWD/cmake-3.2.3-Linux-x86_64/bin:$PATH; fi
   - sudo apt-get update -qq
-  - sudo apt-get install -qq -y unixodbc-dev libmysqlclient-dev g++-arm-linux-gnueabi g++-arm-linux-gnueabihf clang-3.5 sloccount cppcheck 
+  - sudo apt-get install -qq -y unixodbc-dev libmysqlclient-dev g++-arm-linux-gnueabi g++-arm-linux-gnueabihf clang-3.5 libc++-dev sloccount cppcheck
 
 services:
   - mongodb

CMakeLists.txt

@@ -70,6 +70,10 @@ else()
     endif()
 endif()
 
+if (CMAKE_CXX_COMPILER_ID STREQUAL "Clang")
+    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -stdlib=libc++")
+endif()
+
 
 if(NOT MSVC_IDE)
   if(NOT CMAKE_BUILD_TYPE)

cmake/CXX1x.cmake

@@ -18,7 +18,7 @@
 # OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 # THE SOFTWARE.
 
-# Determines whether or not the compiler supports C++11
+# Determines whether the compiler supports C++11
 macro(check_for_cxx11_compiler _VAR)
     message(STATUS "Checking for C++11 compiler")
     set(${_VAR})
@@ -37,9 +37,10 @@ endmacro()
 macro(enable_cxx11)
     set (CMAKE_CXX_STANDARD 11)
     set (CMAKE_CXX_STANDARD_REQUIRED ON)
+    add_definitions(-DPOCO_ENABLE_CPP11)
 endmacro()
 
-# Determines whether or not the compiler supports C++11
+# Determines whether the compiler supports C++14
 macro(check_for_cxx14_compiler _VAR)
     message(STATUS "Checking for C++14 compiler")
     set(${_VAR})
@@ -58,4 +59,5 @@ endmacro()
 macro(enable_cxx14)
     set (CMAKE_CXX_STANDARD 14)
     set (CMAKE_CXX_STANDARD_REQUIRED ON)
+    add_definitions(-DPOCO_ENABLE_CPP14)
 endmacro()