remove stdlib flag from compile command; default to libstdc++

setup.py

@@ -15,10 +15,6 @@
                  if (not req.startswith(('#', 'hg+', 'git+'))
                      and len(req.strip()) > 0)]
 
-# Since OSX Mavericks, the stdlib has been renamed.  So if we're on OSX, we
-# need to be sure to define which standard c++ library to use.  I don't have
-# access to a pre-Mavericks mac, so hopefully this won't break on someone's
-# older system.  Tested and it works on Mac OSX Catalina.
 compiler_and_linker_args = []
 include_dirs = [numpy.get_include(), 'src/natcap/invest/managed_raster']
 if platform.system() == 'Windows':
@@ -34,7 +30,7 @@
 else:
     library_dirs = []
     compiler_args = []
-    compiler_and_linker_args = ['-stdlib=libc++', '-std=c++20']
+    compiler_and_linker_args = ['-std=c++20']
     library_dirs = [subprocess.run(
         ['gdal-config', '--libs'], capture_output=True, text=True
     ).stdout.split()[0][2:]]  # get the first argument which is the library path