distutils: split CC env var before passing to subprocess

In case CC="ccache gcc" then subprocess would interpret it as one command
and fail to find it. Instead split the command line into separate arguments.

Fixes python#53

Lib/distutils/cygwinccompiler.py

@@ -50,6 +50,7 @@
 import os
 import sys
 import copy
+import shlex
 
 from distutils.unixccompiler import UnixCCompiler
 from distutils.file_util import write_file
@@ -353,5 +354,5 @@ def check_config_h():
 
 def is_cygwincc(cc):
     '''Try to determine if the compiler that would be used is from cygwin.'''
-    out_string = check_output([cc, '-dumpmachine'])
+    out_string = check_output(shlex.split(cc) + ['-dumpmachine'])
     return out_string.strip().endswith(b'cygwin')