[OpenCL] Make global ctor init function a kernel

We need to be able to enqueue internal function that initializes
global constructors on the host side. Therefore it has to be
converted to a kernel.

This change factors out common logic for adding kernel metadata
and moves it from CodeGenFunction to CodeGenModule in order to
make it accessible for the extra use case.

Differential revision: https://reviews.llvm.org/D61488

llvm-svn: 360342
diff --git a/clang/test/CodeGenOpenCLCXX/global_init.cl b/clang/test/CodeGenOpenCLCXX/global_init.cl
new file mode 100644
index 0000000..9452cf6
--- /dev/null
+++ b/clang/test/CodeGenOpenCLCXX/global_init.cl
@@ -0,0 +1,11 @@
+// RUN: %clang_cc1 %s -triple spir -cl-std=c++ -emit-llvm -O0 -o - | FileCheck %s
+
+struct S {
+  S() {}
+};
+
+S s;
+
+//CHECK: define internal spir_kernel void @_GLOBAL__sub_I_{{.*}}!kernel_arg_addr_space [[ARGMD:![0-9]+]] !kernel_arg_access_qual [[ARGMD]] !kernel_arg_type [[ARGMD]] !kernel_arg_base_type [[ARGMD]] !kernel_arg_type_qual [[ARGMD]]
+// Check that parameters are empty.
+//CHECK: [[ARGMD]] = !{}