Add Makefile options to build for the Raspberry Pi (armv7=0, arm_fpu=vfp2).

With these Makefile changes, it is possible to build V8 on the Raspberry Pi with the following make invocation:

make native armv7=false vfp3=off hardfp=on disassembler=on console=readline snapshot=on gdbjit=on strictaliasing=off

R=danno@chromium.org
BUG=

Review URL: https://chromiumcodereview.appspot.com/11722003
Patch from Luis Reis <luis.m.reis@gmail.com>.

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@13297 ce2b1a6d-e550-0410-aec6-3dcde31c8c00