Increase length of 'reference' array in xc_write (#451)

* Increased length of 'reference' buffer in xc_write to avaoid LIBXC HSE06
crashes

* Ran make -j pretty

src/xc_write_output.F

@@ -45,9 +45,9 @@ SUBROUTINE xc_write(output_unit, xc_section, lsd)
 
       CHARACTER(len=*), PARAMETER :: routineN = 'xc_write', routineP = moduleN//':'//routineN
 
-      CHARACTER(LEN=10*default_string_length)            :: reference
       CHARACTER(LEN=2*default_string_length)             :: shortform
       CHARACTER(LEN=20)                                  :: tmpStr
+      CHARACTER(LEN=20*default_string_length)            :: reference
       INTEGER                                            :: i_rep, ifun, il, myfun, n_rep
       TYPE(section_vals_type), POINTER                   :: libxc_fun, xc_fun, xc_fun_section