Extern/dolphin headers are not included in m2c context

[r-burns]

Extern/dolphin headers are not included by our m2ctx script, so m2c is unaware of low-level structs and functions it should know. This gives suboptimal output for code that calls into dolphin functions.

It should be possible to fix m2ctx with something like this, but last time I tried this it caused failures in some of our CI jobs:

--- a/tools/m2ctx/m2ctx.py
+++ b/tools/m2ctx/m2ctx.py
@@ -10,6 +10,8 @@ from typing import List
 here = Path(__file__).parent
 root = (here / "../../").resolve()
 src = root / "src"
+extern_dolphin_include = root / "extern" / "dolphin" / "include"
+extern_dolphin = root / "extern" / "dolphin" / "include" / "dolphin"
 build = root / "build"
 header_path = build / "ctx.h"
 source_path = build / "ctx.c"
@@ -80,7 +82,8 @@ PCPP_FLAGS = [
 
 
 def write_header(path: Path):
-    files = sorted({f"#include <{file.relative_to(src)}>" for file in src.rglob("*.h")})
+    files = [f"#include <{file.relative_to(src)}>" for file in src.rglob("*.h")]
+    files += [f"#include <{file.relative_to(extern_dolphin_include)}>" for file in extern_dolphin.rglob("*.h")]
     path.write_text("\n".join(files), encoding="utf-8")