sh: Fix validation of system call number

The slow path for traced system call entries accessed a wrong memory
location to get the number of the maximum allowed system call number.
Renumber the numbered "local" label for the correct location to avoid
collisions with actual local labels.

Signed-off-by: Michael Karcher <kernel@mkarcher.dialup.fu-berlin.de>
Tested-by: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Fixes: f3a83088 ("sh: Add a few missing irqflags tracing markers.")
Signed-off-by: Rich Felker <dalias@libc.org>