Teach llvm-lto to respect the given RelocModel.

Patch by Nick Tomlinson!

llvm-svn: 206177
diff --git a/llvm/include/llvm-c/lto.h b/llvm/include/llvm-c/lto.h
index 049c4d7..808de03 100644
--- a/llvm/include/llvm-c/lto.h
+++ b/llvm/include/llvm-c/lto.h
@@ -79,7 +79,8 @@
 typedef enum {
     LTO_CODEGEN_PIC_MODEL_STATIC         = 0,
     LTO_CODEGEN_PIC_MODEL_DYNAMIC        = 1,
-    LTO_CODEGEN_PIC_MODEL_DYNAMIC_NO_PIC = 2
+    LTO_CODEGEN_PIC_MODEL_DYNAMIC_NO_PIC = 2,
+    LTO_CODEGEN_PIC_MODEL_DEFAULT        = 3
 } lto_codegen_model;
 
 /** opaque reference to a loaded object module */