h8300: Make bloader work with ELF toolchain

h8300: Make bloader work with ELF toolchain

Do not use PIC (position independent code) hacks in boot loader. Compile
it for fixed address and use different LMA and VMA in the linker scripts.
So far, only linker script for h8eurobot board was updated!

Bootstraping was tested with both 32 and 64 bit hosts and it works, despite
that 64 bit compiler produces a lot of warnings such as:
/tmp/cco5hbea.s:1218: Warning: operand #0xffffffffffffffef out of range.