[dev.cc] runtime: bring back mgc0.h

This was recorded as an hg mv instead of an hg cp.
For now a C version is needed for the Go compiler.

TBR=r
CC=golang-codereviews
https://golang.org/cl/174020043

diff --git a/src/runtime/mgc0.h b/src/runtime/mgc0.h
new file mode 100644 (file)
index 0000000..62726b4
--- /dev/null
+++ b/src/runtime/mgc0.h
@@ -0,0 +1,20 @@
+// Copyright 2012 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Used by cmd/gc.
+
+enum {
+       gcBits = 4,
+       BitsPerPointer = 2,
+       BitsDead = 0,
+       BitsScalar = 1,
+       BitsPointer = 2,
+       BitsMask = 3,
+       PointersPerByte = 8/BitsPerPointer,
+       MaxGCMask = 64,
+       insData = 1,
+       insArray,
+       insArrayEnd,
+       insEnd,
+};