Makefile: remove an out-of-date comment

This comment added in dfea575 (Makefile: lazily compute header
dependencies, 2010-01-26) has been out of date since
92b88eb (Makefile: use `git ls-files` to list header files, if
possible, 2019-03-04), when we did exactly what it tells us not to do
and added $(GENERATED_H) to $(OBJECTS) dependencies.

The rest of it was also somewhere between inaccurate and outdated,
since as of b8ba629 (Makefile: fold MISC_H into LIB_H, 2012-06-20)
it's not followed by a list of header files, that got moved earlier in
the file into LIB_H in 60d24dd (Makefile: fold XDIFF_H and VCSSVN_H
into LIB_H, 2012-07-06).

Let's just remove it entirely, to the extent that we have anything
useful to say here the comment on the
"USE_COMPUTED_HEADER_DEPENDENCIES" variable a few lines above this
change does the job for us.

Signed-off-by: Ævar Arnfjörð Bjarmason <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: avar

Makefile

@@ -2501,13 +2501,6 @@ ifneq ($(dep_files_present),)
 include $(dep_files_present)
 endif
 else
-# Dependencies on header files, for platforms that do not support
-# the gcc -MMD option.
-#
-# Dependencies on automatically generated headers such as command-list.h
-# should _not_ be included here, since they are necessary even when
-# building an object for the first time.
-
 $(OBJECTS): $(LIB_H) $(GENERATED_H)
 endif