build: replace WERROR with CMAKE_COMPILE_WARNING_AS_ERROR

-Werror is added to the previous releases job, given it runs on Ubuntu
22.04, which uses an older CMake.

`--compile-no-warning-as-error` can be used, if needed, in future, to
suppress the `CMAKE_COMPILE_WARNING_AS_ERROR` behaviour from a CI
config.

CMAKE_COMPILE_WARNING_AS_ERROR was added to CMake in 3.24.
See https://cmake.org/cmake/help/latest/prop_tgt/COMPILE_WARNING_AS_ERROR.html.

Co-authored-by: willcl-ark <will8clark@gmail.com>

CMakeLists.txt

@@ -119,7 +119,6 @@ endif()
 cmake_dependent_option(BUILD_WALLET_TOOL "Build bitcoin-wallet tool." ${BUILD_TESTS} "ENABLE_WALLET" OFF)
 
 option(REDUCE_EXPORTS "Attempt to reduce exported symbols in the resulting executables." OFF)
-option(WERROR "Treat compiler warnings as errors." OFF)
 option(WITH_CCACHE "Attempt to use ccache for compiling." ON)
 
 option(WITH_ZMQ "Enable ZMQ notifications." OFF)
@@ -568,19 +567,6 @@ if(REDUCE_EXPORTS)
   try_append_linker_flag("-Wl,-no_exported_symbols" VAR CMAKE_EXE_LINKER_FLAGS)
 endif()
 
-if(WERROR)
-  if(MSVC)
-    set(werror_flag "/WX")
-  else()
-    set(werror_flag "-Werror")
-  endif()
-  try_append_cxx_flags(${werror_flag} TARGET core_interface SKIP_LINK RESULT_VAR compiler_supports_werror)
-  if(NOT compiler_supports_werror)
-    message(FATAL_ERROR "WERROR set but ${werror_flag} is not usable.")
-  endif()
-  unset(werror_flag)
-endif()
-
 # Prefer Unix-style package components over frameworks on macOS.
 # This improves compatibility with Python version managers.
 set(Python3_FIND_FRAMEWORK LAST CACHE STRING "")
@@ -685,7 +671,7 @@ message("Cross compiling ....................... ${cross_status}")
 message("C++ compiler .......................... ${CMAKE_CXX_COMPILER_ID} ${CMAKE_CXX_COMPILER_VERSION}, ${CMAKE_CXX_COMPILER}")
 include(FlagsSummary)
 flags_summary()
-message("Treat compiler warnings as errors ..... ${WERROR}")
+message("Treat compiler warnings as errors ..... ${CMAKE_COMPILE_WARNING_AS_ERROR}")
 message("Use ccache for compiling .............. ${WITH_CCACHE}")
 message("\n")
 if(configure_warnings)