I was trying to upgrade ghostscript-gpl-nox11 to the last version (8.60) but the build fails with this error:
--------------------------------------------------------------------------------
./obj/gdevvglb.o(.text+0x9d0): In function `gs_shared_init':
: multiple definition of `gs_shared_init'
./obj/gdevl256.o(.text+0x750): first defined here
gmake: *** [bin/gs] Error 1
*** Error code 2

Stop in /usr/ports/print/ghostscript-gpl-nox11.
--------------------------------------------------------------------------------

So I've tried with ghostscript-gpl, obtaining this error:
--------------------------------------------------------------------------------./obj/gdevl256.o(.text+0x750): In function `gs_shared_init':
: multiple definition of `gs_shared_init'
./obj/gdevxalt.o(.text+0x17a0): first defined here
/usr/bin/ld: Warning: size of symbol `gs_shared_init' changed from 150 in ./obj/gdevxalt.o to 38 in ./obj/gdevl256.o
./obj/gdevvglb.o(.text+0x9d0): In function `gs_shared_init':
: multiple definition of `gs_shared_init'
./obj/gdevxalt.o(.text+0x17a0): first defined here
gmake: *** [bin/gs] Error 1
*** Error code 2

Stop in /usr/ports/print/ghostscript-gpl.
--------------------------------------------------------------------------------

So I figured out that the problem could be the use of WITH_SVGALIB=1 (I have it in pkgtools.conf and it worked for the previous versions).
In fact I had it built avoiding the usage of that flag.

Finally, looking at files/patch-src__devs.mak, I figured out that the problem could be in the selection of both these drivers from the configuration dialog:
- lvga256   SVGAlib, 256-color VGA modes
- vgalib    SVGAlib, 16-color VGA modes
In fact, selecting only the first, ended with a successfully build.
Unfortunately they are both selected by default using make configure WITH_SVGALIB=1, anyway it was used to be ok for the previous versions.

How-To-Repeat: $ cd /usr/ports/print/ghostscript-gpl
$ make WITH_SVGALIB=1

note the both lvga256 and vgalib are selected and proceed with the build