[Bug-apl] ⍕ not respect ⎕PP at some cases

[Xiao-Yong Jin]

Here is a peculiar case,

      ⎕PP
17
      {⍕'PI',○2}
PI 6.2831853071795862
      {⍕'PI' '2PI',[1.5]○1 2}
 PI  3.141592654 
 2PI 6.283185307 
      'PI' '2PI',[1.5]○1 2
 PI  3.1415926535897931 
 2PI 6.2831853071795862