Fix issue #439: Boot to Windows installer not working in UEFI mode.

Copy /efi/boot/bootx64.efi (from Windows ISO) to /EFI/BOOT_WINDOWS/
bootx64.efi in usb (to avoid grub's /efi/boot/bootx64.efi). In UEFI
mode, chainload it instead of bootmgr.efi.

data/multibootusb/grub/win.cfg

@@ -34,14 +34,14 @@ if [ ${grub_platform} == "efi" ]; then
 		}
 	fi
 
-	if [ -e /bootmgr.efi ]; then
-		menuentry "Microsoft Windows Vista/7/8/8.1 UEFI Boot (bootmgr.efi)" {
+	if [ -e /EFI/BOOT_WINDOWS/bootx64.efi ]; then
+		menuentry "Microsoft Windows Vista/7/8/8.1 UEFI Boot (bootx64.efi)" {
 			insmod part_gpt
 			insmod fat
 			insmod search_fs_uuid
 			insmod chain
 			# search --fs-uuid --set=root $hints_string $fs_uuid
-			chainloader /bootmgr.efi
+			chainloader /EFI/BOOT_WINDOWS/bootx64.efi
 		}
 	fi
 

scripts/update_cfg_file.py

@@ -412,7 +412,13 @@ def update_distro_cfg_files(iso_link, usb_disk, distro, persistence=0):
         shutil.copy2(resource_path(os.path.join("data", "EFI", "BOOT", "bootx64.efi")),
                                    os.path.join(config.usb_mount, 'EFI', 'BOOT'))
     elif gen.grub_efi_exist(efi_grub_img) is False:
-        gen.log('EFI image overwritten by distro install. Replacing it now...')
+        if distro == "Windows":
+            gen.log('EFI image overwritten by Windows install. Moving it now...')
+            dst = os.path.join(config.usb_mount, 'EFI', 'BOOT_WINDOWS')
+            os.makedirs(dst)
+            shutil.move(efi_grub_img, dst)
+        else:
+            gen.log('EFI image overwritten by distro install. Replacing it now...')
         shutil.copy2(resource_path(os.path.join("data", "EFI", "BOOT", "bootx64.efi")),
                      os.path.join(config.usb_mount, 'EFI', 'BOOT'))
     else: