Adds support for assembly files and updates the LINE_PATTERN so it
supports both "cmd" and "savedcmd", which allows reverting the U-Boot
modification in commit 97fbb2eb ("scripts/gen_compile_commands.py:
adapt _LINE_PATTERN").

Upstream commits:

- 880946158b011 gen_compile_commands.py: fix path resolve with symlinks in it
- 9e56d3be4bfd2 gen_compile_commands: Sort output compile commands by file name
- 52c15e7e79285 gen_compile_commands: Allow the line prefix to still be cmd_
- 1c67921444bf6 gen_compile_commands: add assembly files to compilation database

Signed-off-by: Brandon Maier <brandon.maier@collins.com>
Cc: Joao Marcos Costa <jmcosta944@gmail.com>