scripts/bloat-o-meter: count weak symbol sizes

Currently, bloat-o-meter does not take into account weak symbols, and
thus ignores any size changes in code or data marked __weak.

Fix this by handling weak code ("w"/"W") and data ("v"/"V").

Link: https://lkml.kernel.org/r/a1e7abd2571c3bbfe75345d6ee98b276d2d5c39d.1692200010.git.geert+renesas@glider.be


Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>