integrate change#18320 from maint-5.6 branch

C<require '\foo\bar.pm'> fails on windows if not running
from the root directory; for a test case, see:

    http://bugs.activestate.com/show_bug.cgi?id=19317

this was due to not recognizing \foo\bar.pm as an absolute
path name
p4raw-link: @18320 on //depot/maint-5.6/perl: b900fc1

p4raw-id: //depot/perl@18321
p4raw-integrated: from //depot/maint-5.6/perl@18319 'merge in' util.h
	(@9288..)

util.h

@@ -17,9 +17,8 @@
 #else		/* !VMS */
 #  ifdef WIN32
 #    define PERL_FILE_IS_ABSOLUTE(f) \
-	(*(f) == '/'							\
-	 || ((f)[0] && (f)[1] == ':')		/* drive name */	\
-	 || ((f)[0] == '\\' && (f)[1] == '\\'))	/* UNC path */
+	(*(f) == '/' || *(f) == '\\'		/* UNC/rooted path */	\
+	 || ((f)[0] && (f)[1] == ':'))		/* drive name */
 #  else		/* !WIN32 */
 #  ifdef NETWARE
 #    define PERL_FILE_IS_ABSOLUTE(f) \