build: speedup by avoiding unnecessary dependencies on generated headers

This prevents the generation of these headers from also depending on the
dependencies of the libs/binaries which consume them.

Specifically, this prevents generated test headers (such as
test/data/base58_encode_decode.json.h) from depending on the
dependencies of test_bitcoin (libcrc32c.a libcrc32c_sse42.a libleveldb.a)

Note that this is currently only relevant for Ninja.

For more detail, see:
https://cmake.org/cmake/help/latest/command/add_custom_command.html

cmake/module/GenerateHeaders.cmake

@@ -2,12 +2,19 @@
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or https://opensource.org/license/mit/.
 
+if(CMAKE_VERSION VERSION_GREATER_EQUAL 3.27)
+  set(DEPENDS_EXPLICIT_OPT DEPENDS_EXPLICIT_ONLY)
+else()
+  set(DEPENDS_EXPLICIT_OPT)
+endif()
+
 function(generate_header_from_json json_source_relpath)
   add_custom_command(
     OUTPUT ${CMAKE_CURRENT_BINARY_DIR}/${json_source_relpath}.h
     COMMAND ${CMAKE_COMMAND} -DJSON_SOURCE_PATH=${CMAKE_CURRENT_SOURCE_DIR}/${json_source_relpath} -DHEADER_PATH=${CMAKE_CURRENT_BINARY_DIR}/${json_source_relpath}.h -P ${PROJECT_SOURCE_DIR}/cmake/script/GenerateHeaderFromJson.cmake
     DEPENDS ${CMAKE_CURRENT_SOURCE_DIR}/${json_source_relpath} ${PROJECT_SOURCE_DIR}/cmake/script/GenerateHeaderFromJson.cmake
     VERBATIM
+    ${DEPENDS_EXPLICIT_OPT}
   )
 endfunction()
 
@@ -17,5 +24,6 @@ function(generate_header_from_raw raw_source_relpath raw_namespace)
     COMMAND ${CMAKE_COMMAND} -DRAW_SOURCE_PATH=${CMAKE_CURRENT_SOURCE_DIR}/${raw_source_relpath} -DHEADER_PATH=${CMAKE_CURRENT_BINARY_DIR}/${raw_source_relpath}.h -DRAW_NAMESPACE=${raw_namespace} -P ${PROJECT_SOURCE_DIR}/cmake/script/GenerateHeaderFromRaw.cmake
     DEPENDS ${CMAKE_CURRENT_SOURCE_DIR}/${raw_source_relpath} ${PROJECT_SOURCE_DIR}/cmake/script/GenerateHeaderFromRaw.cmake
     VERBATIM
+    ${DEPENDS_EXPLICIT_OPT}
   )
 endfunction()