arm: Always build the NEON SIMD code when targetting ARMv7-A devices.

arm: Always build the NEON SIMD code when targetting ARMv7-A devices.

The libjpeg_turbo library only uses the NEON SIMD code path when it
determines at runtime that the CPU supports it. Always enable it when
targetting ARMv7-A devices.

Tested on a Motorola Xoom (Tegra2, thus no Neon) and on a Nexus S
(supports Neon).

Benchmarking shows a x1.48 decoding performance improvement on the
Nexus S, and x1.09 on a Galaxy Nexus.

BUG=
TEST=

The original change is created by digit@chromium.org.
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=144411