Implement missing bits to support lazy binding. Note that the code

Implement missing bits to support lazy binding.  Note that the code
deliberately does not save the floating-point argument registers
before calling _dl_bind().  Doing so would force an FPU context switch
upon every function call through the PLT.  But since we compile ld.so
with -march=armv8-a+nofp+nosimd this is safe since nothing in the _dl_bind()
codepath uses he FPU registers.

ok guenther@, drahn@