[shuffle] Move utils to new structure.

The name `core` was decided fit better with the base language for the
IR. This CL moves the `core/` folder to `utils/` and moves the files
into the correct subdirectories. The build targets and namespaces are
not updated as part of the move and will be fixed up in later CLs.

Bug: tint:1988
Change-Id: I1fc4414c86b28e1669af2d2d07340ecfdd9ba681
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/142361
Reviewed-by: Ben Clayton <bclayton@google.com>
Kokoro: Kokoro <noreply+kokoro@google.com>
diff --git a/src/tint/utils/debug/debugger.cc b/src/tint/utils/debug/debugger.cc
new file mode 100644
index 0000000..0cb6b59
--- /dev/null
+++ b/src/tint/utils/debug/debugger.cc
@@ -0,0 +1,62 @@
+// Copyright 2022 The Tint Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "src/tint/utils/debug/debugger.h"
+
+#ifdef TINT_ENABLE_BREAK_IN_DEBUGGER
+
+#ifdef _MSC_VER
+#include <Windows.h>
+#elif defined(__linux__)
+#include <signal.h>
+#include <fstream>
+#include <string>
+#endif
+
+#ifdef _MSC_VER
+#define TINT_DEBUGGER_BREAK_DEFINED
+void tint::debugger::Break() {
+    if (::IsDebuggerPresent()) {
+        ::DebugBreak();
+    }
+}
+
+#elif defined(__linux__)
+
+#define TINT_DEBUGGER_BREAK_DEFINED
+void tint::debugger::Break() {
+    // A process is being traced (debugged) if "/proc/self/status" contains a
+    // line with "TracerPid: <non-zero-digit>...".
+    bool is_traced = false;
+    std::ifstream fin("/proc/self/status");
+    std::string line;
+    while (!is_traced && std::getline(fin, line)) {
+        const char kPrefix[] = "TracerPid:\t";
+        static constexpr int kPrefixLen = sizeof(kPrefix) - 1;
+        if (line.length() > kPrefixLen && line.compare(0, kPrefixLen, kPrefix) == 0) {
+            is_traced = line[kPrefixLen] != '0';
+        }
+    }
+
+    if (is_traced) {
+        raise(SIGTRAP);
+    }
+}
+#endif  // platform
+
+#endif  // TINT_ENABLE_BREAK_IN_DEBUGGER
+
+#ifndef TINT_DEBUGGER_BREAK_DEFINED
+void tint::debugger::Break() {}
+#endif