test-resolve: fix '--tool f' invocation for Windows

Windows can't invoke a python script directly, so invoke sh.exe instead.

According to sid0, the output changes are due to the fact that 'f' is no longer
being passed all of the args that it was, but these changes aren't essential to
the test [1].

[1] https://selenic.com/pipermail/mercurial-devel/2015-November/075768.html

tests/test-resolve.t

@@ -221,21 +221,7 b' resolve <file> should re-merge file'
 
 test .orig behavior with resolve
 
-  $ hg resolve -q file1 --tool 'f --dump $TESTTMP/repo/file1.orig'
-  */file1~base*: (glob)
-  >>>
-  foo
-  <<<
-  */file1~other*: (glob)
-  >>>
-  foo
-  bar
-  <<<
-  $TESTTMP/repo/file1: (glob)
-  >>>
-  foo
-  baz
-  <<<
+  $ hg resolve -q file1 --tool "sh -c 'f --dump \"$TESTTMP/repo/file1.orig\"'"
   $TESTTMP/repo/file1.orig: (glob)
   >>>
   foo