[AArch64, Falkor] Switch to using Falkor-specific vector costs.

[AArch64, Falkor] Switch to using Falkor-specific vector costs.

The adjusted vector costs give Falkor a reasonable boost in performance for FP
benchmarks (both CPU2017 and CPU2006) and doesn't change INT benchmarks that
much. There are some regressions that will be investigated as follow on work.

Numbers from the CI run:

CPU2017:

(R) 605.mcf_s: -1.8%
(R) 620.omnetpp_s: -2%
    623.xalancbmk_s: 2%
    654.roms_s: 7%

(R) INT mean: -0.09%
    FP mean: 0.70%

CPU2006:

(R) 429.mc: -5%
(R) 471.omnetpp: -9.5% (potentially noise/fluctuations)
    483.xalancbmk: 6.02%
    410.bwaves: 5.03%
    433.milc: 2%
    434.zeusmp: 10.5%
(R) 436.cactusADM: -12.75%
    437.leslie3d: 5.94%
(R) 453.povray: -0.82%
    459.GemsFDTD: 16.87%
    465.tonto: 1%

(R) INT mean: -0.79%
    FP mean: 1.54%

gcc/ChangeLog:

2018-08-08  Luis Machado  <luis.machado@linaro.org>

	* config/aarch64/aarch64.c (qdf24xx_vector_cost): New static global.
	(qdf24xx_tunings): Set vector cost structure to qdf24xx_vector_cost.

From-SVN: r263389