configure: Fix problem with linking on OS X 10.7.

Some of the new link commands in the latest ld appear to be buggy and cause
bus error while initializing libSystem. Fixed by reverting to 10.6 linking
behavior.
diff --git a/configure.ac b/configure.ac
index 8104f7f..ecd74d6 100644
--- a/configure.ac
+++ b/configure.ac
@@ -697,7 +697,12 @@
     AC_SUBST(COREFOUNDATIONLIB,"-framework CoreFoundation")
     AC_SUBST(IOKITLIB,"-framework IOKit -framework CoreFoundation")
     AC_SUBST(APPLICATIONSERVICESLIB,"-framework ApplicationServices")
-    AC_SUBST(LDEXECFLAGS,["-image_base 0x7bf00000 -Wl,-segaddr,WINE_DOS,0x00001000,-segaddr,WINE_SHAREDHEAP,0x7f000000"])
+    case $host_os in
+      darwin11*)
+        AC_SUBST(LDEXECFLAGS,["-image_base 0x7bf00000 -Wl,-macosx_version_min,10.6,-segaddr,WINE_DOS,0x00001000,-segaddr,WINE_SHAREDHEAP,0x7f000000"]) ;;
+      *)
+        AC_SUBST(LDEXECFLAGS,["-image_base 0x7bf00000 -Wl,-segaddr,WINE_DOS,0x00001000,-segaddr,WINE_SHAREDHEAP,0x7f000000"]) ;;
+    esac
     if test "$ac_cv_header_DiskArbitration_DiskArbitration_h" = "yes"
     then
         dnl DiskArbitration API is not public on Darwin < 8.0, use it only if header found