Fix failure of unittests/ExecutionEngine/JIT/MultiJITTest.cpp on
cygwin when built with ENABLE_SHARED=1.  Patch by NAKAMURA Takumi!


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@111231 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/System/DynamicLibrary.cpp b/lib/System/DynamicLibrary.cpp
index 6f6890c..660db49 100644
--- a/lib/System/DynamicLibrary.cpp
+++ b/lib/System/DynamicLibrary.cpp
@@ -70,6 +70,12 @@
     if (ErrMsg) *ErrMsg = dlerror();
     return true;
   }
+#ifdef __CYGWIN__
+  // Cygwin searches symbols only in the main
+  // with the handle of dlopen(NULL, RTLD_GLOBAL).
+  if (Filename == NULL)
+    H = RTLD_DEFAULT;
+#endif
   if (OpenedHandles == 0)
     OpenedHandles = new std::vector<void *>();
   OpenedHandles->push_back(H);