gen_compile_commands: handle multiple lines per .mod file

scripts/clang-tools/gen_compile_commands.py incorrectly assumes that
each .mod file only contains one line. That assumption was correct when
the script was originally created, but commit 9413e764 ("kbuild:
split the second line of *.mod into *.usyms") changed the .mod file
format so that there is one entry per line, and potentially many lines.

The problem can be reproduced by using Kbuild to generate
compile_commands.json, like this:

    make CC=clang compile_commands.json

In many cases, the problem might be overlooked because many subsystems
only have one line anyway. However, in some subsystems (Nouveau, with
762 entries, is a notable example) it results in skipping most of the
subsystem.

Fix this by fully processing each .mod file.

Fixes: 9413e764 ("kbuild: split the second line of *.mod into *.usyms")
Signed-off-by: John Hubbard <jhubbard@nvidia.com>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

scripts/clang-tools/gen_compile_commands.py

@@ -157,10 +157,10 @@ def cmdfiles_for_modorder(modorder):
             if ext != '.ko':
                 sys.exit('{}: module path must end with .ko'.format(ko))
             mod = base + '.mod'
-	    # The first line of *.mod lists the objects that compose the module.
+            # Read from *.mod, to get a list of objects that compose the module.
             with open(mod) as m:
-                for obj in m.readline().split():
-                    yield to_cmdfile(obj)
+                for mod_line in m:
+                    yield to_cmdfile(mod_line.rstrip())
 
 
 def process_line(root_directory, command_prefix, file_path):