ARM: Makefile/gyp update allowing better control of ARM specific options.

ARM: Makefile/gyp update allowing better control of ARM specific options.

This patch defines new makefile command line paramaters to better control the
ARM specific options. The new paramters are
 * armfpu      = vfp, vfpv3-d16, vfpv3, neon.
 * armfloatabi = softfp, hard
 * armneon     = on
 * armthumb    = on, off
 * armtest     = on
One existing paratemer has been modified:
 * armv7       = true, false
A number of parameters have been deprecated (but are still working):
 * hardfp      = on, off
 * vfp2        = off
 * vfp3        = off

the armtest paratmer when set to "on" will lock the options used during compile
time at runtime. This allows for example to easily test the ARMv6 build on an
ARMv7 platform without having to worry about features detected at runtime. When
not specified the compiler default will be used meaning it is not necessary
anymore to specify hardfp=on when natively building on an hardfp platform.

The shell help now prints the target options and features detected.

BUG=none
TEST=none

Review URL: https://chromiumcodereview.appspot.com/14263018

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@14288 ce2b1a6d-e550-0410-aec6-3dcde31c8c00