server: Fix an invalid memory access in subtract_overlapping (Valgrind).

[Sebastian Lackner]

Signed-off-by: Sebastian Lackner <sebastian at fds-team.de>
---

The equivalent to f3560ece31d59f1aaba2c2fef2487bccb1f20d96 for the wineserver.

 server/region.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/server/region.c b/server/region.c
index 464c5ad..33e2a54 100644
--- a/server/region.c
+++ b/server/region.c
@@ -469,7 +469,8 @@ static int subtract_overlapping( struct region *pReg,
                 rect->bottom = bottom;
             }
             r1++;
-            left = r1->left;
+            if (r1 != r1End)
+                left = r1->left;
         }
     }
 
-- 
2.7.0