Restore test files accidentally deleted in r354839

I think there must be a bug in git-llvm causing parent directories to be
deleted when the diff deletes files in a subdirectory. Perhaps it is
Windows-only.

There has been a behavior change, so some of these tests now fail. I
have marked them XFAIL and will fix them in a follow-up to separate the
changes.

llvm-svn: 360699
diff --git a/clang/test/ASTMerge/function/Inputs/function1.c b/clang/test/ASTMerge/function/Inputs/function1.c
new file mode 100644
index 0000000..4523bd3
--- /dev/null
+++ b/clang/test/ASTMerge/function/Inputs/function1.c
@@ -0,0 +1,6 @@
+void f0(int);
+void f1(int, float);
+void f2();
+void f3(void);
+void f4(int, int);
+int f5(int) __attribute__((const));