rs6000: Use brace blocks in define_insn

rs6000: Use brace blocks in define_insn

This patch changes the remaining cases in our machine description files
to use brace blocks instead of double-quoted strings as the output
control string.  This increases readability by making the blocks look
more like normal C code, mostly because backslash quoting is no longer
needed.  It also removes such quoting where it was still there (usually
harmless but always confusing). and it writes "\n\t" as "\;" in one
place where we didn't already.

	* config/rs6000/altivec.md: Write output control strings as braced
	blocks instead of double-quoted strings.
	* config/rs6000/darwin.md: Ditto.
	* config/rs6000/rs6000.md: Ditto.
	* config/rs6000/vector.md: Ditto.
	* config/rs6000/vsx.md: Ditto.

From-SVN: r257889