cmake: build crypto_plugins only when needed for radosgw

Make crypto_plugins a conditional ALL target instead of an explicit
dependency to improve build parallelism.

Background:
- dbbf052: Added crypto plugins with ceph_crypto_isal as os dependency
- 53726b8: Changed os to depend on crypto_plugins (not specific plugin)
- Issue:
  * crypto_plugins are not dependencys of "os" at all
  * crypto_plugins are runtime-only dependencies for rgw_common

In this change:

- Remove crypto_plugins from explicit target dependencies
- Add crypto_plugins to ALL target when WITH_RADOSGW=ON
- Plugins now build in parallel with other targets
- Maintains runtime plugin loading without compile-time coupling

This improves build concurrency by allowing crypto_plugins to build
in parallel with os/rgw_common instead of sequentially, and prevents
building crypto plugins when RadosGW is disabled.

Signed-off-by: Kefu Chai <[email protected]>

Author: tchaikov

src/CMakeLists.txt

@@ -873,8 +873,6 @@ if(WITH_TESTS)
   add_subdirectory(test)
 endif()
 
-add_subdirectory(crypto)
-
 if(WITH_TESTS)
   install(PROGRAMS
     ${CMAKE_RUNTIME_OUTPUT_DIRECTORY}/ceph-debugpack
@@ -1147,6 +1145,7 @@ if(WITH_RADOSGW)
     endif(WITH_SYSTEM_ARROW)
   endif(WITH_RADOSGW_SELECT_PARQUET OR WITH_RADOSGW_ARROW_FLIGHT)
 
+  add_subdirectory(crypto)
   add_subdirectory(libkmip)
   add_subdirectory(rgw)
 endif(WITH_RADOSGW)

src/crypto/CMakeLists.txt

@@ -1,4 +1,5 @@
-add_custom_target(crypto_plugins)
+# crypto plugins are loaded at runtime by rgw_crypt.cc
+add_custom_target(crypto_plugins ALL)
 set(crypto_plugin_dir ${CEPH_INSTALL_PKGLIBDIR}/crypto)
 
 add_subdirectory(openssl)

src/os/CMakeLists.txt

@@ -41,8 +41,6 @@ if(WITH_JAEGER)
     PRIVATE jaeger_base)
 endif()
 
-add_dependencies(os crypto_plugins)
-
 if(WITH_BLUESTORE)
   add_executable(ceph-bluestore-tool
     bluestore/bluestore_tool.cc)