Win32: Fix default prefix

The old code resulted in wrong escape sequences:

#define CONFIG_QEMU_SHAREDIR "c:\Program Files\Qemu"

gcc warnings:

vl.c:5708:20: warning: unknown escape sequence '\P'
vl.c:5708:20: warning: unknown escape sequence '\Q'

Windows can handle slash (/) path separators,
and QEMU already adds directories using slash,
so there is no need to fight with the correct number
of backslashes.
Signed-off-by: NStefan Weil <weil@mail.berlios.de>
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>
Message-Id: 

configure

@@ -1393,7 +1393,7 @@ fi
 
 if test "$mingw32" = "yes" ; then
   if test -z "$prefix" ; then
-      prefix="c:\\\\Program Files\\\\Qemu"
+      prefix="c:/Program Files/Qemu"
   fi
   mansuffix=""
   datasuffix=""