build: the vendored HLS headers no longer warn, and three stale CMake rules go

Four unrelated but equally small build-tree fixes, none of which changes what
any binary does:

* fpga/hls: `fpga/include/` holds the vendored Xilinx `ap_int`/`ap_fixed`
  headers. Included with a plain `-I` they emit 790 default-visible
  `-Wdeprecated-enum-enum-conversion` warnings across the targets that consume
  them - every warning a developer sees in a build of the receiver, the broker,
  the tests or the HLS simulation comes from that one header. `SYSTEM`
  propagates as `-isystem`, silencing the vendored header while leaving warnings
  in our own HLS sources visible. Measured on one HLS source: 78 -> 0 at default
  flags, 289 -> 56 under -Wall.

* compression: `zstd/lib` was the old in-tree vendored location, gone from the
  tree since zstd moved to FetchContent. It stays harmless only while nothing
  sits there; a checkout with a leftover `compression/zstd/` puts that copy's
  internal headers (`common/huf.h`, `common/mem.h`) ahead of the fetched zstd
  the library actually links. The fetched zstd already exports its `lib/` root,
  so dropping the entry is all that is needed.

* xds-plugin: `target_link_options(... --exclude-libs,ALL)` was applied twice,
  once unconditionally and once guarded by `if(UNIX AND NOT APPLE)`. Keep the
  guarded one.

* xds-plugin's install rule uses `CMAKE_INSTALL_LIBDIR`, which was only ever set
  as a side effect of a fetched dependency including GNUInstallDirs first.
  Include it at the top level, where it belongs.

* broker: `redoc-static.html` was installed to `<prefix>/jfjoch/frontend/`, a
  path nothing serves - the broker mounts its frontend from
  `share/jfjoch/frontend`, whose copy of the API reference is `dist/openapi.html`
  written by `npm run redocly`, while `redoc-static.html` itself reaches the
  bundle through Sphinx's `html_static_path`.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_011GxZqDiFP3KqriBhNdcR56

CMakeLists.txt

@@ -10,6 +10,7 @@ STRING(REGEX MATCH "^[0-9]+\\.[0-9]+\\.[0-9]+" JFJOCH_VERSION_NUMERIC "${JFJOCH_
 
 PROJECT(jfjoch VERSION ${JFJOCH_VERSION_NUMERIC} LANGUAGES C CXX)
 SET(CMAKE_POLICY_DEFAULT_CMP0077 NEW)
+INCLUDE(GNUInstallDirs)
 
 SET(CMAKE_CXX_STANDARD 20)
 SET(CMAKE_CXX_STANDARD_REQUIRED True)

broker/CMakeLists.txt

@@ -1,6 +1,3 @@
-# OpenAPI definition
-INSTALL(FILES redoc-static.html DESTINATION jfjoch/frontend COMPONENT jfjoch )
-
 # OpenAPI model
 AUX_SOURCE_DIRECTORY(gen/model MODEL_SOURCES)
 ADD_LIBRARY(JFJochAPI STATIC ${MODEL_SOURCES})

compression/CMakeLists.txt

@@ -19,4 +19,4 @@ ADD_LIBRARY(Compression STATIC
 set_target_properties(Compression PROPERTIES POSITION_INDEPENDENT_CODE ON)
 TARGET_COMPILE_DEFINITIONS(Compression PUBLIC -DZSTD_SUPPORT -DUSE_ZSTD)
 TARGET_LINK_LIBRARIES(Compression libzstd_static)
-TARGET_INCLUDE_DIRECTORIES(Compression PUBLIC . zstd/lib)
+TARGET_INCLUDE_DIRECTORIES(Compression PUBLIC .)

fpga/hls/CMakeLists.txt

@@ -39,7 +39,7 @@ ADD_LIBRARY( JFJochHLSCores STATIC
         ptp.cpp)
 
 TARGET_COMPILE_DEFINITIONS(JFJochHLSCores PUBLIC -DJFJOCH_HLS_NOSYNTH)
-TARGET_INCLUDE_DIRECTORIES(JFJochHLSCores PUBLIC ../include)
+TARGET_INCLUDE_DIRECTORIES(JFJochHLSCores SYSTEM PUBLIC ../include)
 
 IF(VIVADO_HLS)
     IF(NOT HLS_SOLUTION_NAME)

xds-plugin/CMakeLists.txt

@@ -3,10 +3,6 @@ ADD_LIBRARY(jfjoch_xds_plugin SHARED plugin.cpp plugin.h)
 TARGET_LINK_LIBRARIES(jfjoch_xds_plugin JFJochHDF5Wrappers JFJochVersion Compression hdf5-static)
 INSTALL(TARGETS jfjoch_xds_plugin DESTINATION ${CMAKE_INSTALL_LIBDIR}/jfjoch COMPONENT viewer)
 
-target_link_options(jfjoch_xds_plugin PRIVATE
-        "LINKER:--exclude-libs,ALL"
-)
-
 set_target_properties(jfjoch_xds_plugin PROPERTIES
         CXX_VISIBILITY_PRESET hidden
         C_VISIBILITY_PRESET hidden