Merge #235: [FIXUP] cmake: Link Threads::Threads to `core_base_inte…

…rface`

0772957 [FIXUP] cmake: Link `Threads::Threads` to `core_base_interface` (Hennadii Stepanov)

Pull request description:

  This PR fixes compiling using `-pthread` flag on UNIX systems with a non-POSIX default thread model.

  Details:

  1. During tests on SunOS / illumos (OpenIndiana Hipster 2024.04 distribution), wallet-specific unit tests and benchmarks exhibited deadlock-like behavior. It [seems](https://gitlab.kitware.com/cmake/cmake/-/issues/26063) that POSIX threads were expected but not properly utilized.

  2. Despite applying a patch to CMake, the staging branch continued to fail due to a bug that is resolved with this PR.

  ---

  UPD. Currently, a workaround can be applied: `-DAPPEND_CPPFLAGS="-pthread"`.

ACKs for top commit:
  fanquake:
    ACK 0772957

Tree-SHA512: c2e219792bb79b355d34335f19efb9a1adc81e7eeb9bc2b7aaa1b35967bffdbced5d887a00892b5d43b035998ee689d9c9263298f789b04826da6537b37b002b

CMakeLists.txt

@@ -314,8 +314,11 @@ if(CMAKE_SYSTEM_NAME STREQUAL "Darwin")
   endif()
 endif()
 
-include(AddThreadsIfNeeded)
-add_threads_if_needed()
+set(THREADS_PREFER_PTHREAD_FLAG ON)
+find_package(Threads REQUIRED)
+target_link_libraries(core_base_interface INTERFACE
+  Threads::Threads
+)
 
 if(SANITIZERS)
   # First check if the compiler accepts flags. If an incompatible pair like

src/util/CMakeLists.txt

@@ -47,6 +47,5 @@ target_link_libraries(bitcoin_util
     core_interface
     bitcoin_clientversion
     bitcoin_crypto
-    Threads::Threads
     $<$<PLATFORM_ID:Windows>:ws2_32>
 )