Adds support for ARM softfp calling convention.

Adds support for ARM softfp calling convention.

The cross-compiler with the Android NDK doesn't support
the 'hard' calling convention, so we need both. I've
added a preprocessor define to the gyp file for the
standalone vm indicating support for 'hard' so that I
don't have to modify the Dartium gyp files.

R=srdjan@google.com

Committed: https://code.google.com/p/dart/source/detail?r=29577

[zra, 2013-10-30 18:24:47]

Regis's hair is on fire, so:

-regis
+srdjan,asiva.

[srdjan, 2013-10-30 18:39:22]

lgtm

[zra, 2013-10-30 18:58:00]

Committed patchset #2 manually as r29577 (presubmit successful).