Update to netpbm-9.5.

Update to netpbm-9.5.
Fixes pkg/8949.
Changes:
o Extend formats to allow multiple images per file.  Add -allimages
  option to pnmfile.  Add pnmsplit.  Extend pnmtops.
o Add pbmtowbmp, wbmptopbm.  Thanks Terje Sannum.
o ppmtobmp: Add 24 bit (truecolor) capability.
o pnmcut: easier, more expressive syntax for specifying what to cut.
o pnminterp: handle maxval != 255, convert to use Netpbm libraries.
o Translate pstopnm from Csh to C, eliminate dependency on the 'bc'
  program.
o Fix bug in tiff library build which caused null soname.
o Add optParseopt2() to shhopt.a so you can use long options with one
  hyphen instead of two.
o giftopnm: fix bug with variable used before set.  Fix bug (coding
  error -- 0=>i).  Unknown impact.
o bmptoppm: fix bug with 24 bit (truecolor) Windows BMPs.
o xwdtopnm: fix one more bug with bits_per_item <> bits_per_pixel.
o Fix ppmtompeg build bug with static libraries.
o Make build clean with gcc -ansi (albeit with some files that need
  extensions declaring the _BSD_SOURCE etc.).
o Rebase pnmtopng, pngtopnm on Pnmtopng 2.37.4.
o pbmtolj: fix bug where blank lines get discarded.  Thanks Charles
  Howes.
o ppmtompeg: fix bug with "PNM" format files with maxval != 255. Get
  rid of built-in PPM file parsing.
o Fix 'make install' where mkinstalldirs is not found.
o Fix bug where rle_global.c would not compile with GNU C Library 2.