Fix for Bug 686961 - Can't open a PDF file in GS 8_10 (but it works in GS 8_00).

Reviewers,

When an MS TrueType Format 2.0 font does not have Glyph names data, the 
rangecheck error occurs.

Following code segment (line 461-467 in gs_ttf.ps) is for building Glyph

names array for MS TrueType Format 2.0,

      [ numglyphs 1 sub {
	postglyphs postpos get <-----
        postglyphs postpos 1 add 2 index getinterval cvn
	exch postpos add 1 add /postpos exch def
	postpos postglyphs length ge { exit } if
      } repeat
      ] /postnames exch def

/postpos is the pointer value for the position where Glyph names data 
starts. When Glyph names data is not included in a font, /postpos value
is 
equal to the length of the whole 'post' table data (/postglyphs) and
'get' 
operator in the second line of the code segment above makes invalid
access 
to the data.

To avoid this situation mentioned, I moved the termination condition 
checking code in the last of the loop to the first.

      [ numglyphs 1 sub {
	postpos postglyphs length ge { exit } if <-----
	postglyphs postpos get
        postglyphs postpos 1 add 2 index getinterval cvn
	exch postpos add 1 add /postpos exch def
      } repeat
      ] /postnames exch def

Now the condition checking code makes the process exit the loop when
Glyph 
names data is not available and no error occurs.

Jeong

Log:
When Glyph names data is not available for a TrueType Format 2.0 font, 
rangecheck error occured. Now fixed. Bug#686961.