cmake: build shared libexecutorch_quantized_ops when EXECUTORCH_BUILD_SHARED=ON

Create a single libexecutorch_quantized_ops.so that bundles
quantized_ops_lib and quantized_kernels, allowing consumers to link
quantized op implementations via a shared library.

quantized_ops_lib already has --whole-archive as an INTERFACE link
option from Codegen.cmake, so we do not wrap it in
$<LINK_LIBRARY:WHOLE_ARCHIVE,...> to avoid pulling the registration
constructor in twice. Link against executorch_shared (not
executorch_core) to share a single operator registry.

Co-authored-by: Claude <noreply@anthropic.com>

Author: tomeuv

kernels/quantized/CMakeLists.txt

@@ -157,3 +157,34 @@ install(
   PUBLIC_HEADER
     DESTINATION ${CMAKE_INSTALL_INCLUDEDIR}/executorch/kernels/quantized/
 )
+
+# When building shared libraries, create a single
+# libexecutorch_quantized_ops.so that bundles quantized_ops_lib and
+# quantized_kernels so consumers can link a shared library instead of
+# needing --whole-archive on the static archives.
+if(EXECUTORCH_BUILD_SHARED)
+  file(WRITE ${CMAKE_CURRENT_BINARY_DIR}/quantized_ops_shared_empty.cpp
+       "// intentionally empty"
+  )
+  add_library(
+    executorch_quantized_ops SHARED
+    ${CMAKE_CURRENT_BINARY_DIR}/quantized_ops_shared_empty.cpp
+  )
+  # quantized_ops_lib already has --whole-archive as an INTERFACE link option
+  # (from executorch_target_link_options_shared_lib in Codegen.cmake), so do
+  # NOT wrap it in $<LINK_LIBRARY:WHOLE_ARCHIVE,...> to avoid double pull-in.
+  target_link_libraries(
+    executorch_quantized_ops
+    PRIVATE quantized_ops_lib
+            quantized_kernels
+            executorch_shared
+  )
+  set_target_properties(
+    executorch_quantized_ops PROPERTIES LINKER_LANGUAGE CXX
+  )
+  install(
+    TARGETS executorch_quantized_ops
+    EXPORT ExecuTorchTargets
+    LIBRARY DESTINATION ${CMAKE_INSTALL_LIBDIR}
+  )
+endif()