MSP430: Remove do_no_relax_short_jumps

MSP430: Remove do_no_relax_short_jumps

This is an old cludge from from when the Binutils linker could not relax
BR to JMP and vice-versa when shuffling "either" sections between upper
and lower memory. This has been fixed since at least Binutils 2.30.

gcc/ChangeLog:

	* config/msp430/msp430-protos.h (msp430_do_not_relax_short_jumps):
	Remove.
	* config/msp430/msp430.c (msp430_do_not_relax_short_jumps): Likewise.
	* config/msp430/msp430.md (cbranchhi4_real): Remove special case for
	msp430_do_not_relax_short_jumps.