Enables you to link against the combined ARM and Thumb library.
--thumb2_library only applies
when the processor supports ARM and Thumb-2 technology, such as
the Cortex-A and Cortex-R series processors.
--no_thumb2_library option to revert
to the ARMv5T and later libraries.
The linker ignores
--thumb2_library if the
target does not support Thumb-2 technology.