Modify linux-arm.mk to support the armv4t architecture instead of armv4.

armv4 was only implemented on StrongArm and Arm8 (See http://en.wikipedia.org/wiki/ARM_architecture)
and will be more difficult to support since it does not support the bx instruction.
armv4t on the other hand is used in a wide range of cpu:s.
armv4 is also not supported by bionic or dalvik, but armv4t is.

Thumb-mode is not yet enabled since there are some unresolved abi-issues.