[mac/clang/libc++/c++11] force clang to use libc++ for c++11, instead of the default old libstdc++4.2.1 which doesn't support c++11

cython/gtsam/setup.py.in

@@ -2,6 +2,12 @@ from distutils.core import setup
 from distutils.extension import Extension
 from Cython.Build import cythonize
 import eigency
+from sys import platform
+
+# force clang use libc++ instead of the default libstdc++ shipped with MacOSX, which doesn't support c++11
+libc_flag = []
+if platform == "darwin":
+    libc_flag = ["-stdlib=libc++"]
 
 setup(
   ext_modules = cythonize(Extension(
@@ -13,5 +19,6 @@ setup(
     libraries = ['gtsam'],
     library_dirs = ["${CMAKE_BINARY_DIR}/gtsam"],
     language="c++",
-    extra_compile_args=["-std=c++11"])),
+    extra_compile_args=["-std=c++11"] + libc_flag,
+    extra_link_args=libc_flag)),
 )

cython/gtsam_unstable/setup.py.in

@@ -7,6 +7,10 @@ import sys
 # so that it can find the wrapped gtsam package
 sys.path.append("..")
 
+libc_flag = []
+if sys.platform == "darwin":
+    libc_flag = ["-stdlib=libc++"]
+
 setup(
     ext_modules=cythonize(Extension(
         "gtsam_unstable",
@@ -17,6 +21,7 @@ setup(
         libraries=['gtsam', 'gtsam_unstable'],
         library_dirs=["${GTSAM_DIR}/../../"],
         language="c++",
-        extra_compile_args=["-std=c++11"])),
+        extra_compile_args=["-std=c++11"] + libc_flag,
+        extra_link_args=libc_flag)),
 )