[clang-ifs] Clang Interface Stubs, first version.

Clang interface stubs (previously referred to as clang-ifsos) is a new frontend
action in clang that allows the generation of stub files that contain mangled
name info that can be used to produce a stub library. These stub libraries can
be useful for breaking up build dependencies and controlling access to a
library's internal symbols. Generation of these stubs can be invoked by:

clang -fvisibility=<visibility> -emit-interface-stubs \
                                -interface-stub-version=<interface format>

Notice that -fvisibility (along with use of visibility attributes) can be used
to control what symbols get generated. Currently the interface format is
experimental but there are a wide range of possibilities here.

Differential Revision: https://reviews.llvm.org/D60974

llvm-svn: 363626
diff --git a/clang/test/InterfaceStubs/inline.h b/clang/test/InterfaceStubs/inline.h
new file mode 100644
index 0000000..fe16519
--- /dev/null
+++ b/clang/test/InterfaceStubs/inline.h
@@ -0,0 +1,4 @@
+INLINE int bar() {
+  static int var = 42;
+  return var;
+}