o Introduced usage of the mksysmap script.
o Improved the non-verbose output to look like this:
  BTFIX   arch/sparc/boot/btfix.S
  AS      arch/sparc/boot/btfix.o
  LD      arch/sparc/boot/image
  SYSMAP  arch/sparc/boot/System.map

o No longer generate System.map for each build
o Use normal AS rule to compile btfix.S
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>