Merge #259: cmake: Silent "Policy CMP0167 is not set"

b3448f1 fixup! cmake: Build `bitcoind` executable (Hennadii Stepanov)

Pull request description:

  This PR silents a developer warning when using >=CMake 3.30.

  Closes #257.

ACKs for top commit:
  theuni:
    ACK b3448f1

Tree-SHA512: 6a11db220df55ef44ce7121ca1751a918686394ea76c440457d1d87f359c48bccfae807045975f520805a39bae40d9e85d088e627edf54047793d5c0e741e29e

cmake/module/AddBoostIfNeeded.cmake

@@ -17,6 +17,14 @@ function(add_boost_if_needed)
   directory and other added INTERFACE properties.
   ]=]
 
+  # We cannot rely on find_package(Boost ...) to work properly without
+  # Boost_NO_BOOST_CMAKE set until we require a more recent Boost because
+  # upstream did not ship proper CMake files until 1.82.0.
+  # Until then, we rely on CMake's FindBoost module.
+  # See: https://cmake.org/cmake/help/latest/policy/CMP0167.html
+  if(POLICY CMP0167)
+    cmake_policy(SET CMP0167 OLD)
+  endif()
   set(Boost_NO_BOOST_CMAKE ON)
   find_package(Boost 1.73.0 REQUIRED)
   mark_as_advanced(Boost_INCLUDE_DIR)