CMake: Fix definition of LTDL_SHLIB_EXT for Darwin.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@82530 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 4e48ef6..684d3d0 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -145,7 +145,11 @@
   if(UNIX)
     set(LLVM_ON_WIN32 0)
     set(LLVM_ON_UNIX 1)
-    set(LTDL_SHLIB_EXT ".so")
+    if(APPLE)
+      set(LTDL_SHLIB_EXT ".dylib")
+    else(APPLE)
+      set(LTDL_SHLIB_EXT ".so")
+    endif(APPLE)
     set(EXEEXT "")
     # FIXME: Maximum path length is currently set to 'safe' fixed value
     set(MAXPATHLEN 2024)