configure: define "arm_fpu" and "arm_neon" for ARM
configure: define "arm_fpu" and "arm_neon" for ARM

v8's common.gypi file expects them to be defined now.

Closes #4534.

dreamllq/node,dreamllq/node,dreamllq/node,dreamllq/node,dreamllq/node,dreamllq/node,dreamllq/node,dreamllq/node,dreamllq/node