glsl/linker: Fix xfb stride alignment for buffers containing 64bit types

Per OpenGL 4.6 spec:
"If no xfb_stride qualifier is specified for a
 binding point, the stride is derived by identifying the variable associated with the
 binding point having the largest offset, and then adding the offset and the size of
 the variable, in basic machine units. If any variable associated with the binding
 point contains double-precision floating-point components, the derived stride is
 aligned to the next multiple of eight basic machine units. If a binding point has no
 xfb_stride qualifier and no associated output variables, its stride is zero."

Reviewed-by: Tapani Pälli <tapani.palli@intel.com>
Signed-off-by: Andrii Simiklit <andrii.simiklit@globallogic.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/2333>

src/compiler/glsl/link_varyings.h

@@ -106,8 +106,8 @@ public:
               struct gl_transform_feedback_info *info, unsigned buffer,
               unsigned buffer_index, const unsigned max_outputs,
               BITSET_WORD *used_components[MAX_FEEDBACK_BUFFERS],
-              bool *explicit_stride, bool has_xfb_qualifiers,
-              const void *mem_ctx) const;
+              bool *explicit_stride, unsigned *max_member_alignment,
+              bool has_xfb_qualifiers, const void *mem_ctx) const;
    const tfeedback_candidate *find_candidate(gl_shader_program *prog,
                                              hash_table *tfeedback_candidates);
    void set_lowered_candidate(const tfeedback_candidate *candidate);