[Cygwin] Fix global variable dll import

Author: Berrysoft

llvm/lib/Target/TargetMachine.cpp

@@ -204,7 +204,7 @@ bool TargetMachine::shouldAssumeDSOLocal(const GlobalValue *GV) const {
     // don't assume the variables to be DSO local unless we actually know
     // that for sure. This only has to be done for variables; for functions
     // the linker can insert thunks for calling functions from another DLL.
-    if (TT.isWindowsGNUEnvironment() && GV->isDeclarationForLinker() &&
+    if (TT.isOSCygMing() && GV->isDeclarationForLinker() &&
         isa<GlobalVariable>(GV))
       return false;