gen_compile_commands: fix invalid escape sequence warning

[ Upstream commit dae4a017 ]

With python 3.12, '\#' results in this warning
    SyntaxWarning: invalid escape sequence '\#'

Signed-off-by: Andrew Ballance <andrewjballance@gmail.com>
Reviewed-by: Justin Stitt <justinstitt@google.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>