[MinGW] Enable large file for mingw-w64

64-bit mingw doesn't define _FILE_OFFSET_BITS=64 by default.

Differential Revision: https://reviews.llvm.org/D53569

llvm-svn: 345131
diff --git a/llvm/cmake/modules/HandleLLVMOptions.cmake b/llvm/cmake/modules/HandleLLVMOptions.cmake
index 2787578..05db1b0 100644
--- a/llvm/cmake/modules/HandleLLVMOptions.cmake
+++ b/llvm/cmake/modules/HandleLLVMOptions.cmake
@@ -224,6 +224,10 @@
   append_if(SUPPORTS_FVISIBILITY_INLINES_HIDDEN_FLAG "-fvisibility-inlines-hidden" CMAKE_CXX_FLAGS)
 endif()
 
+if(CMAKE_SIZEOF_VOID_P EQUAL 8 AND MINGW)
+  add_definitions( -D_FILE_OFFSET_BITS=64 )
+endif()
+
 if( CMAKE_SIZEOF_VOID_P EQUAL 8 AND NOT WIN32 )
   # TODO: support other platforms and toolchains.
   if( LLVM_BUILD_32_BITS )