glsl/types: Fix function type comparison function

It was returning true if the function types have different lengths rather
than false.  This was new with the SPIR-V to NIR pass and I thought I'd
fixed it a while ago but it may have gotten lost in rebasing somewhere.

Signed-off-by: Jason Ekstrand <jason@jlekstrand.net>
Reviewed-by: Iago Toral Quiroga <itoral@igalia.com>
Cc: "12.0" <mesa-stable@lists.freedesktop.org>

src/compiler/glsl_types.cpp

@@ -1086,7 +1086,7 @@ function_key_compare(const void *a, const void *b)
    const glsl_type *const key2 = (glsl_type *) b;
 
    if (key1->length != key2->length)
-      return 1;
+      return false;
 
    return memcmp(key1->fields.parameters, key2->fields.parameters,
                  (key1->length + 1) * sizeof(*key1->fields.parameters)) == 0;