External weak linkage is supported by recent binutils on mingw32.

llvm-svn: 34519
diff --git a/llvm/lib/Target/X86/X86TargetAsmInfo.cpp b/llvm/lib/Target/X86/X86TargetAsmInfo.cpp
index 20e0f19..23cab9d 100644
--- a/llvm/lib/Target/X86/X86TargetAsmInfo.cpp
+++ b/llvm/lib/Target/X86/X86TargetAsmInfo.cpp
@@ -131,6 +131,7 @@
     // Set up DWARF directives
     HasLEB128 = true;  // Target asm supports leb128 directives (little-endian)
     PrivateGlobalPrefix = "L";  // Prefix for private global symbols
+    WeakRefDirective = "\t.weak\t";
     DwarfRequiresFrameSection = false;
     DwarfAbbrevSection =  "\t.section\t.debug_abbrev,\"dr\"";
     DwarfInfoSection =    "\t.section\t.debug_info,\"dr\"";