Merge bitcoin/bitcoin#31543: cmake: Always provide RPATH on NetBSD

11115e9 cmake: Always provide `RPATH` on NetBSD (Hennadii Stepanov)

Pull request description:

  Apparently, runtime paths cannot be skipped on NetBSD, even for system-wide packages.

  On NetBSD 10.0:
  - on the master branch @ bb57017:
  ```
  $ cmake -B build -DCMAKE_C_COMPILER="/usr/pkg/gcc14/bin/gcc" -DCMAKE_CXX_COMPILER="/usr/pkg/gcc14/bin/g++"
  $ cmake --build build
  $ ./build/src/bitcoin-wallet -version
  ./build/src/bitcoin-wallet: Shared object "libsqlite3.so.0" not found
  $ cmake --install build --prefix /home/hebasto/INSTALL
  $ /home/hebasto/INSTALL/bin/bitcoin-wallet -version
  /home/hebasto/INSTALL/bin/bitcoin-wallet: Shared object "libsqlite3.so.0" not found
  ```
  - with this PR:
  ```
  $ cmake -B build -DCMAKE_C_COMPILER="/usr/pkg/gcc14/bin/gcc" -DCMAKE_CXX_COMPILER="/usr/pkg/gcc14/bin/g++"
  $ cmake --build build
  $ ./build/src/bitcoin-wallet -version | head -1
  Bitcoin Core bitcoin-wallet utility version v28.99.0-11115e9aa845
  $ cmake --install build --prefix /home/hebasto/INSTALL
  $ /home/hebasto/INSTALL/bin/bitcoin-wallet -version | head -1
  Bitcoin Core bitcoin-wallet utility version v28.99.0-11115e9aa845
  ```

ACKs for top commit:
  theuni:
    utACK bitcoin/bitcoin@11115e9

Tree-SHA512: c9cd5d8c65fcf12677c381060dd53794396b7cd3e61ec39d3c5dadd7cdc08ab9790c59aa346402d53f8f9f317830919edf7f8135a6c0d5703c3bd9e519b157a4

CMakeLists.txt

@@ -580,8 +580,13 @@ endif()
 # Relevant discussions:
 # - https://github.com/hebasto/bitcoin/pull/236#issuecomment-2183120953
 # - https://github.com/bitcoin/bitcoin/pull/30312#issuecomment-2191235833
-set(CMAKE_SKIP_BUILD_RPATH TRUE)
-set(CMAKE_SKIP_INSTALL_RPATH TRUE)
+# NetBSD always requires runtime paths to be set for executables.
+if(CMAKE_SYSTEM_NAME STREQUAL "NetBSD")
+  set(CMAKE_INSTALL_RPATH_USE_LINK_PATH TRUE)
+else()
+  set(CMAKE_SKIP_BUILD_RPATH TRUE)
+  set(CMAKE_SKIP_INSTALL_RPATH TRUE)
+endif()
 add_subdirectory(test)
 add_subdirectory(doc)