microsoft/clc: Add unreachable() to fix 'may be unitialized' warning
In function ‘lower_load_kernel_input’,
inlined from ‘clc_nir_lower_kernel_input_loads’ at ../src/microsoft/clc/clc_nir.c:205:28:
../src/microsoft/clc/clc_nir.c:169:7: warning: ‘base_type’ may be used uninitialized [-Wmaybe-uninitialized]
169 | glsl_vector_type(base_type, nir_dest_num_components(intr->dest));
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
../src/microsoft/clc/clc_nir.c: In function ‘clc_nir_lower_kernel_input_loads’:
../src/microsoft/clc/clc_nir.c:151:24: note: ‘base_type’ was declared here
151 | enum glsl_base_type base_type;
| ^~~~~~~~~