glsl: Swap the order of glsl_type::name and ::length

glsl: Swap the order of glsl_type::name and ::length

On x86-64 this saves 8 bytes of padding in the structure, and this
reduces the size of the structure to 32 bytes.

v2: Fix constructor so that GCC won't warn about the order of
initialization.

Signed-off-by: Ian Romanick <ian.d.romanick@intel.com>
Reviewed-by: Brian Paul <brianp@vmware.com>
Reviewed-by: Tapani Pälli <tapani.palli@intel.com>