Remove lto_codegen_set_attr.

It was never exported, so no functionality change.

llvm-svn: 214519
diff --git a/llvm/include/llvm-c/lto.h b/llvm/include/llvm-c/lto.h
index 51079896..c525710 100644
--- a/llvm/include/llvm-c/lto.h
+++ b/llvm/include/llvm-c/lto.h
@@ -40,7 +40,7 @@
  * @{
  */
 
-#define LTO_API_VERSION 11
+#define LTO_API_VERSION 10
 
 /**
  * \since prior to LTO_API_VERSION=3
@@ -375,14 +375,6 @@
 extern void
 lto_codegen_set_cpu(lto_code_gen_t cg, const char *cpu);
 
-/**
- * Sets attributes for the cpu to generate code for.
- *
- * \since LTO_API_VERSION=11
- */
-extern void
-lto_codegen_set_attr(lto_code_gen_t cg, const char *attr);
-
 
 /**
  * Sets the location of the assembler tool to run. If not set, libLTO