[REFACTOR][RUNTIME][RPC] Move minrpc/ into src/runtime/rpc/minrpc/

minrpc implements a minimal RPC protocol that shares rpc_reference.h
with the standard RPC transport in src/runtime/rpc/. Nesting minrpc/
under rpc/ makes that structural relationship explicit on the file
system and removes it from the runtime top-level.

Changes:
- src/runtime/minrpc/ → src/runtime/rpc/minrpc/ (3 files + posix_popen_server/)
- rpc_endpoint.h, rpc_session.h: "../minrpc/rpc_reference.h" → "minrpc/rpc_reference.h"
- disco/protocol.h, process_session.cc, threaded_session.cc:
  "../minrpc/rpc_reference.h" → "../rpc/minrpc/rpc_reference.h"
- hexagon/rpc/{hexagon,simulator}/rpc_server.cc:
  "../../../minrpc/minrpc_server.h" → "../../../rpc/minrpc/minrpc_server.h"
- CMakeLists.txt: RUNTIME_SRCS glob src/runtime/minrpc/*.cc → src/runtime/rpc/minrpc/*.cc
- cmake/modules/Hexagon.cmake: two explicit header list entries updated
- python/tvm/rpc/minrpc.py: path constant for -I flag and server.cc source
  updated from src/runtime/minrpc to src/runtime/rpc/minrpc

Header guards in minrpc_server.h and rpc_reference.h already encode
TVM_RUNTIME_MINRPC_*, which remain correct after the move.

Author: tqchen

CMakeLists.txt

@@ -344,7 +344,7 @@ tvm_file_glob(GLOB RUNTIME_SRCS
   src/runtime/*.cc
   src/runtime/vm/*.cc
   src/runtime/memory/*.cc
-  src/runtime/minrpc/*.cc
+  src/runtime/rpc/minrpc/*.cc
 )
 # Note: src/runtime/disco/** moves to libtvm_runtime_extra.
 # Note: src/runtime/{cuda,vulkan,opencl,metal,rocm,hexagon}/* move to per-backend DSOs.

cmake/modules/Hexagon.cmake

@@ -289,8 +289,8 @@ if(USE_HEXAGON_RPC)
 
     # Include the generic RPC code into the TVM runtime.
     list(APPEND RUNTIME_HEXAGON_SRCS
-      "${TVMRT_SOURCE_DIR}/minrpc/minrpc_server.h"
-      "${TVMRT_SOURCE_DIR}/minrpc/rpc_reference.h"
+      "${TVMRT_SOURCE_DIR}/rpc/minrpc/minrpc_server.h"
+      "${TVMRT_SOURCE_DIR}/rpc/minrpc/rpc_reference.h"
       "${TVMRT_SOURCE_DIR}/rpc/rpc_module.cc"
       "${TVMRT_SOURCE_DIR}/rpc/rpc_endpoint.cc"
       "${TVMRT_SOURCE_DIR}/rpc/rpc_session.cc"

python/tvm/rpc/minrpc.py

@@ -39,7 +39,7 @@ def find_minrpc_server_libpath(server="posix_popen_server"):
     """
     curr_dir = os.path.dirname(os.path.realpath(os.path.expanduser(__file__)))
     source_dir = os.path.abspath(os.path.join(curr_dir, "..", "..", ".."))
-    minrpc_dir = os.path.join(source_dir, "src", "runtime", "minrpc")
+    minrpc_dir = os.path.join(source_dir, "src", "runtime", "rpc", "minrpc")
     path = os.path.join(minrpc_dir, server, f"{server}.cc")
 
     candidates = [path]

src/runtime/disco/process_session.cc

@@ -27,7 +27,7 @@
 #include <vector>
 
 #include "../../support/pipe.h"
-#include "../minrpc/rpc_reference.h"
+#include "../rpc/minrpc/rpc_reference.h"
 #include "./bcast_session.h"
 #include "./disco_worker_thread.h"
 #include "./message_queue.h"

src/runtime/disco/protocol.h

@@ -33,7 +33,7 @@
 #include "../../support/arena.h"
 #include "../../support/base64.h"
 #include "../../support/bytes_io.h"
-#include "../minrpc/rpc_reference.h"
+#include "../rpc/minrpc/rpc_reference.h"
 
 namespace tvm {
 namespace runtime {

src/runtime/disco/threaded_session.cc

@@ -29,7 +29,7 @@
 #include <utility>
 
 #include "../../support/ring_buffer.h"
-#include "../minrpc/rpc_reference.h"
+#include "../rpc/minrpc/rpc_reference.h"
 #include "./bcast_session.h"
 #include "./disco_worker_thread.h"
 #include "./protocol.h"

src/runtime/hexagon/rpc/hexagon/rpc_server.cc

@@ -36,7 +36,7 @@ extern "C" {
 #include <memory>
 #include <string>
 
-#include "../../../minrpc/minrpc_server.h"
+#include "../../../rpc/minrpc/minrpc_server.h"
 #include "../../hexagon/hexagon_common.h"
 #include "../../hexagon/hexagon_device_api.h"
 #include "../../profiler/prof_utils.h"

src/runtime/hexagon/rpc/simulator/rpc_server.cc

@@ -28,7 +28,7 @@
 #include <sstream>
 #include <string>
 
-#include "../../../minrpc/minrpc_server.h"
+#include "../../../rpc/minrpc/minrpc_server.h"
 #include "../../hexagon_common.h"
 #include "../../profiler/prof_utils.h"
 #include "hexagon_sim_proto.h"