Automated test failure: union with alignment attrs

[vext01]

In my project, I have this automatically generated test failure:

---- p_ffi::bindgen_test_layout_La_x86_64_vector stdout ----
thread 'p_ffi::bindgen_test_layout_La_x86_64_vector' panicked at 'assertion failed: `(left == right)`
  left: `8`,
 right: `16`: Alignment of La_x86_64_vector', /home/vext01/research/phdrs_pv/target/debug/build/phdrs-766b5f3742f78b0d/out/bindings.rs:7077:5
note: Run with `RUST_BACKTRACE=1` for a backtrace.

Caused by:

/* Registers for entry into PLT on x86-64.  */                                        
# if __GNUC_PREREQ (4,0)                                                              
typedef float La_x86_64_xmm __attribute__ ((__vector_size__ (16)));                   
typedef float La_x86_64_ymm                                                           
    __attribute__ ((__vector_size__ (32), __aligned__ (16)));                         
typedef double La_x86_64_zmm                                                          
    __attribute__ ((__vector_size__ (64), __aligned__ (16)));                         
# else                                                                                
typedef float La_x86_64_xmm __attribute__ ((__mode__ (__V4SF__)));                    
# endif

typedef union                                                                         
{                                                                                     
# if __GNUC_PREREQ (4,0)                                                              
  La_x86_64_ymm ymm[2];                                                               
  La_x86_64_zmm zmm[1];                                                               
# endif                                                                               
  La_x86_64_xmm xmm[4];                                                               
} La_x86_64_vector __attribute__ ((__aligned__ (16)));

As discussed in #1370

Cheers

[emilio]

Fix at #1394.