Refinement by Stefan Krah (see issue 11715, msg133194) to exit early if the

dpkg-architecture command is not found on $PATH.  This should fix the failures
on FreeBSD and Solaris, which do not create the target file via I/O
redirection if the command isn't found (unlike Linux and OS X which do).

setup.py

@@ -373,6 +373,8 @@ class PyBuildExt(build_ext):
     def add_multiarch_paths(self):
         # Debian/Ubuntu multiarch support.
         # https://wiki.ubuntu.com/MultiarchSpec
+        if not find_executable('dpkg-architecture'):
+            return
         tmpfile = os.path.join(self.build_temp, 'multiarch')
         if not os.path.exists(self.build_temp):
             os.makedirs(self.build_temp)