[C API] Add LLVMStructGetTypeAtIndex.

Patch by deadalnix (Amaury SECHET).

llvm-svn: 239029
diff --git a/llvm/include/llvm-c/Core.h b/llvm/include/llvm-c/Core.h
index effbd15..73bff0b 100644
--- a/llvm/include/llvm-c/Core.h
+++ b/llvm/include/llvm-c/Core.h
@@ -998,6 +998,13 @@
 void LLVMGetStructElementTypes(LLVMTypeRef StructTy, LLVMTypeRef *Dest);
 
 /**
+ * Get the type of the element at a given index in the structure.
+ *
+ * @see llvm::StructType::getTypeAtIndex()
+ */
+LLVMTypeRef LLVMStructGetTypeAtIndex(LLVMTypeRef StructTy, unsigned i);
+
+/**
  * Determine whether a structure is packed.
  *
  * @see llvm::StructType::isPacked()