nir: Remove nir_array from lower_locals_to_regs
nir: Remove nir_array from lower_locals_to_regs

We do nothing but initialize it, add to it, and delete it.
This is a fallout from removing constant initializer support.

Reviewed-by: Eric Anholt <96f164ad4d9b2b0dacf8ebee2bb1eeb3aa69adf1@anholt.net>
Reviewed-by: Jason Ekstrand <68c46a606457643eab92053c1c05574abb26f861@jlekstrand.net>

metora/MesaGLSLCompiler,metora/MesaGLSLCompiler,metora/MesaGLSLCompiler