Adapt test and example after e39d1b6f0856.

Tarek’s commit fixed the way packaging configuration file markers are
split under Windows, but these two files were not edited.

Doc/packaging/setupcfg.rst

@@ -779,7 +779,7 @@ needs to have its options defined in a dedicated section.  Here's an example::
    extra_compile_args =
        -fPIC -O2
        -DGECODE_VERSION=$(./gecode_version) -- sys.platform != 'win32'
-       /DGECODE_VERSION='win32' -- sys.platform == 'win32'
+       /DGECODE_VERSION=win32 -- sys.platform == 'win32'
 
 The section name must start with ``extension:``; the right-hand part is used as
 the full name (including a parent package, if any) of the extension.  Whitespace

Lib/packaging/tests/test_config.py

@@ -119,7 +119,7 @@ include_dirs = /usr/include/gecode
     /usr/include/blitz
 extra_compile_args = -fPIC -O2
     -DGECODE_VERSION=$(./gecode_version) -- sys.platform != 'win32'
-    /DGECODE_VERSION='win32' -- sys.platform == 'win32'
+    /DGECODE_VERSION=win32 -- sys.platform == 'win32'
 language = cxx
 
 # corner case: if the parent package of an extension is declared but