libmvec: further unifdef'ing (LIBMVEC_SO_BUILD)

*** 27,41 ****
   */
  
          .file   "__vsqrtf_ultra3.S"
  
  #include "libm.h"
- #if defined(LIBMVEC_SO_BUILD)
          .weak   __vsqrtf
          .type   __vsqrtf,#function
          __vsqrtf = __vsqrtf_ultra3
- #endif
  
          RO_DATA
          .align  64
  
  .CONST_TBL:
--- 27,39 ----