realpath "No such file or directory" warnings when building

[Rustam Kovhaev]

tags from KBUILD_OUTPUT directory
Reply-To: 

running 'make ARCH=x86_64 COMPILED_SOURCE=1 cscope tags' in
KBUILD_OUTPUT directory produces lots of "No such file or directory"
warnings from realpath

it seems like commit 4f491bb6ea2a greatly improved tags generation when
COMPILED_SOURCE=1 is set, but should we add "-q" flag for realpath in 
all_compiled_sources() or probably it would be better to fix root cause
and make sure that for example we don't try to find objtool sources and
exclude other similar dirs during tags generation? what do you think?

...
realpath: special.h: No such file or directory
realpath: warn.h: No such file or directory
realpath: sigchain.c: No such file or directory
realpath: sigchain.h: No such file or directory
realpath: orc_gen.c: No such file or directory
realpath: objtool.c: No such file or directory
...