glsl/builtins: Fix {texture1D,texture2D,shadow1D}ArrayLod availibility.

These functions are defined in EXT_texture_array, which makes no
mention of what shader types they should be allowed in.  At the time
EXT_texture_array was introduced, functions ending in "Lod" were
available only in vertex shaders, however this restriction was lifted
in later spec versions and extensions.

We already have the function lod_exists_in_stage() for figuring out
whether functions ending in "Lod" should be available, so just re-use
that.