build: cmake: add -ffile-prefix-map option

this mirrors what we already have in configure.py.

Signed-off-by: Kefu Chai <kefu.chai@scylladb.com>

Closes scylladb/scylladb#15798

cmake/mode.common.cmake

@@ -78,6 +78,8 @@ function(get_padded_dynamic_linker_option output length)
   set(${output} "${dynamic_linker_option}=${padded_dynamic_linker}" PARENT_SCOPE)
 endfunction()
 
+add_compile_options("-ffile-prefix-map=${CMAKE_SOURCE_DIR}=.")
+
 default_target_arch(target_arch)
 if(target_arch)
   add_compile_options("-march=${target_arch}")