cw: don't shadow pure pre-processing
cw(1onbld): --shadow not --secondary

*** 49,59 ****
  command lines.
  .Sh ARGUMENTS
  Both the
  .Fl -primary
  and
! .Fl -secondary
  parameters take a
  .Em compiler specification .
  This is a comma-separated list of the form
  .Ar name,executable,style
  Where
--- 49,59 ----
  command lines.
  .Sh ARGUMENTS
  Both the
  .Fl -primary
  and
! .Fl -shadow
  parameters take a
  .Em compiler specification .
  This is a comma-separated list of the form
  .Ar name,executable,style
  Where
*** 131,150 ****
  .Nm cw
  will invoke shadow compiler, with the outputs modified (as well as any
  translation for compiler style) as follows:
  .Bl -enum
  .It
! If none of
  .Fl c ,
- .Fl E ,
- .Fl P ,
- or
  .Fl S
! appears in the argument list (that is, linking is attempted), the shadow
! compilers will not be invoked.
! This is because the objects built with that compiler which would be linked
! have been previously discarded.
  .It
  If the
  .Fl o Ar filename
  option was provided, with or without a separating space, it will be replaced with
  .Fl o Ar tempfile
--- 131,145 ----
  .Nm cw
  will invoke shadow compiler, with the outputs modified (as well as any
  translation for compiler style) as follows:
  .Bl -enum
  .It
! If neither of 
  .Fl c ,
  .Fl S
! appears in the argument list (that is, linking is attempted or only the
! pre-processor is invoked), the shadow compilers will not be invoked.
  .It
  If the
  .Fl o Ar filename
  option was provided, with or without a separating space, it will be replaced with
  .Fl o Ar tempfile
*** 163,174 ****
  Messages from the compilers will not be interleaved.
  If
  .Nm cw
  is used to invoke the preprocessor and no output location is specified,
  .Nm cw
! will write to standard output the primary compiler's standard output, and the
! secondary compiler's standard output will be discarded.
  .Pp
  Because the Sun compilers write intermediate objects to fixed
  filenames in the current directory when instructed to compile and
  link multiple source files via a single command line, it would be
  unsafe to invoke more than one compiler in this fashion.
--- 158,168 ----
  Messages from the compilers will not be interleaved.
  If
  .Nm cw
  is used to invoke the preprocessor and no output location is specified,
  .Nm cw
! will write to standard output the primary compiler's standard output.
  .Pp
  Because the Sun compilers write intermediate objects to fixed
  filenames in the current directory when instructed to compile and
  link multiple source files via a single command line, it would be
  unsafe to invoke more than one compiler in this fashion.