glsl: fails to reject shaders that use array-of-void

Glslang compiles this to SPIR-V.
```glsl
#version 320 es
void[2] foo() { }
void main() { foo(); }
```

The GLSL ES 3.2 spec [says](https://registry.khronos.org/OpenGL/specs/es/3.2/GLSL_ES_Specification_3.20.html#basic-types:~:text=The%20keyword%20void%20cannot%20be%20used%20in%20any%20other%20declarations%20(except%20for%20empty%20formal%20or%20actual%20parameter%20lists)%2C%20or%20an%20error%20results.):

> Functions that do not return a value must be declared as *void*. There is no default function return type. The keyword *void* cannot be used in any other declarations (except for empty formal or actual parameter lists), or an error results.

**Glslang should fail compilation of the shader, and emit an error.**

(In the generated spir-v foo returns an OpUndef of type array-of-two-void)

Glslang (correctly) rejects this shader:
```glsl
void[2] bar() { }
void[2] foo() { return bar(); }
void main() { foo(); }
```
producing this error:
```
b.comp
ERROR: b.comp:3: 'return' : void function cannot return a value
ERROR: b.comp:3: '' : compilation terminated
ERROR: 2 compilation errors. No code generated.
```
The error is not quite right, because it implies `foo` is a 'void function'. That quality of the message was quite secondary.

This is super low priority for me. I was just messing around. :-)

Run the provided GLSL ES 3.2 shader through glslang and compare it with the second example that is already rejected. Trace the compiler's validation of function return types and array-of-void declarations. Done means the first shader emits a compilation error instead of producing SPIR-V, while the existing rejection remains valid.

Written by the indexing model from the issue text.