ARM: Support hardfloat in SCons build and make it a build time setting

ARM: Support hardfloat in SCons build and make it a build time setting

Add option armeabi to the SCons build for selecting the floating point variant to use. Also add externally defined CCFLAGS environment for all targets. Run test.py with option -S armeabi=hardfloat to test with hardfloat enabled.

Make selecting hardfloat EABI variant a build-time option instead of a runtime option.

Add a simple check of the EABI variant during V8 initialization to exit if the compilation was not configured correctly. The reason for this is that GCC does not provide a compile time symbol defining the EABI variant. This check is not fool-proof as it cannot check the compilation configuration used for the snapshot if any.

R=karlklose@chromium.org, erik.corry@gmail.com

BUG=none
TEST=none

Review URL: http://codereview.chromium.org//6905098

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@7715 ce2b1a6d-e550-0410-aec6-3dcde31c8c00