Object: Make IRObjectFile own multiple modules and enumerate symbols from all modules.

This implements multi-module support in IRObjectFile.

Differential Revision: https://reviews.llvm.org/D26951

llvm-svn: 289578
diff --git a/llvm/test/Object/multi-module.ll b/llvm/test/Object/multi-module.ll
new file mode 100644
index 0000000..204ffc6
--- /dev/null
+++ b/llvm/test/Object/multi-module.ll
@@ -0,0 +1,8 @@
+; RUN: llvm-cat -o - %s %S/Inputs/multi-module.ll | llvm-nm - | FileCheck %s
+
+; CHECK: T f1
+; CHECK: T f2
+
+define void @f1() {
+  ret void
+}