avoid absolute paths in grpcio-tools install script

Author: h-vetinari

recipe/patches/0011-build-grpcio-tools-from-source.patch

@@ -1,14 +1,14 @@
-From 980d72c700f10ed22db92a51c6a3f925e0325f62 Mon Sep 17 00:00:00 2001
+From de307ec15e9179105ed903a50e206088dd890fa0 Mon Sep 17 00:00:00 2001
 From: "H. Vetinari" <h.vetinari@gmx.com>
 Date: Tue, 4 Mar 2025 08:53:30 +1100
 Subject: [PATCH 11/15] build grpcio-tools from source
 
 ---
- tools/distrib/python/grpcio_tools/setup.py | 43 ++++++++++++++++------
- 1 file changed, 31 insertions(+), 12 deletions(-)
+ tools/distrib/python/grpcio_tools/setup.py | 47 ++++++++++++++++------
+ 1 file changed, 35 insertions(+), 12 deletions(-)
 
 diff --git a/tools/distrib/python/grpcio_tools/setup.py b/tools/distrib/python/grpcio_tools/setup.py
-index fb6c416c96..033a2fe304 100644
+index fb6c416c96..c761c3670e 100644
 --- a/tools/distrib/python/grpcio_tools/setup.py
 +++ b/tools/distrib/python/grpcio_tools/setup.py
 @@ -15,6 +15,7 @@
@@ -54,7 +54,7 @@ index fb6c416c96..033a2fe304 100644
 
  GRPC_PYTHON_TOOLS_PACKAGE = "grpc_tools"
  GRPC_PYTHON_PROTO_RESOURCES_NAME = "_proto"
-@@ -293,16 +293,34 @@ def package_data():
+@@ -293,16 +293,38 @@ def package_data():
      return {GRPC_PYTHON_TOOLS_PACKAGE: proto_files}
 
 
@@ -81,7 +81,11 @@ index fb6c416c96..033a2fe304 100644
      else:
          plugin_sources = [os.path.join("grpc_tools", "_protoc_compiler.cpp")]
 
-+    grpc_root = os.environ["SRC_DIR"]
++    # setuptools requires relative paths; calculate it
++    src_dir = pathlib.Path(os.environ["SRC_DIR"]).resolve()
++    setup_dir = pathlib.Path(__file__).resolve().parent
++    # cannot use pathlib's Path.relative_to to go _out_; see https://github.com/python/cpython/issues/88244
++    grpc_root = pathlib.Path(os.path.relpath(src_dir, setup_dir)).as_posix()
      plugin_sources += [
          os.path.join("grpc_tools", "main.cc"),
 -        os.path.join("grpc_root", "src", "compiler", "python_generator.cc"),
@@ -91,7 +95,7 @@ index fb6c416c96..033a2fe304 100644
      ] + CC_FILES
 
      plugin_ext = Extension(
-@@ -310,10 +328,11 @@ def extension_modules():
+@@ -310,10 +332,11 @@ def extension_modules():
          sources=plugin_sources,
          include_dirs=[
              ".",

recipe/patches/0012-reduce-grpc-symbol-explosion-with-autogenerated-expo.patch

@@ -1,4 +1,4 @@
-From 8d5305b2d1ea793c60a5103901586a996ac53980 Mon Sep 17 00:00:00 2001
+From 8ae0edebd28369b16c4ade7b46b1300871534bbf Mon Sep 17 00:00:00 2001
 From: "H. Vetinari" <h.vetinari@gmx.com>
 Date: Wed, 5 Mar 2025 13:21:01 +1100
 Subject: [PATCH 12/15] reduce grpc symbol explosion with autogenerated export

recipe/patches/0013-update-GRPC_DLL-instances-where-necessary.patch

@@ -1,4 +1,4 @@
-From ec104bab4b2071cbcdad3b39cc551c98243c3fde Mon Sep 17 00:00:00 2001
+From e9a4afe16f406e3e5e8826fce49a0d17a8b8fed1 Mon Sep 17 00:00:00 2001
 From: "H. Vetinari" <h.vetinari@gmx.com>
 Date: Sun, 2 Mar 2025 07:16:19 +1100
 Subject: [PATCH 13/15] update GRPC_DLL instances where necessary

recipe/patches/0014-use-protobuf-s-libutf8_range.patch

@@ -1,4 +1,4 @@
-From 37ade4a10dc8f3454686876368bc61fcbba3e174 Mon Sep 17 00:00:00 2001
+From b55af7374bd39b75cb7a598ef7cac6db17c648be Mon Sep 17 00:00:00 2001
 From: "H. Vetinari" <h.vetinari@gmx.com>
 Date: Sat, 10 Jan 2026 20:43:11 +1100
 Subject: [PATCH 14/15] use protobuf's libutf8_range

recipe/patches/0015-disable-grpc-_unsecure.patch

@@ -1,4 +1,4 @@
-From 0f87806467d72a1c0bfbe3c1f2f035910ac01e52 Mon Sep 17 00:00:00 2001
+From a2bd84cb1484a775e7b934d4b3568d0185b4e838 Mon Sep 17 00:00:00 2001
 From: "H. Vetinari" <h.vetinari@gmx.com>
 Date: Sun, 11 Jan 2026 22:45:25 +1100
 Subject: [PATCH 15/15] disable grpc{,++}_unsecure