fbdev/arm: Export acorndata_8x8 font symbol for bootloader

fbdev/arm: Export acorndata_8x8 font symbol for bootloader

The text display code used in the Risc PC kernel image decompression
code uses arch/arm/boot/compressed/font.c, which includes
lib/fonts/font_acorn_8x8.c, which further includes <linux/font.h>.

Since commit 97df8960240a ("lib/fonts: Provide helpers for calculating
glyph pitch and size") <linux/font.h> contains inline functions that
require __do_div64, which is not linked into the ARM kernel
decompressor. This makes Risc PC zImages fail to build.

Resolve this issue by defining the BOOTLOADER symbol and use it to avoid
a static declaration of the acorndata_8x8 symbol. That way it can be
referenced by the arm bootloader, and other static math functions and
symbols (like __do_div64) stay static and don't get unneccesary included
in the ARM kernel bootloader decompressor object file.

Fixes: 97df8960240a ("lib/fonts: Provide helpers for calculating glyph pitch and size")
Reported-by: Ethan Nelson-Moore <enelsonmoore@gmail.com>
Reviewed-by: Thomas Zimmermann <tzimmermann@suse.de>
Cc: linux-arm-kernel@lists.infradead.org
Cc: Russell King <linux@armlinux.org.uk>
Signed-off-by: Helge Deller <deller@gmx.de>