Mine

cc -o makekeys -O2  -ansi -pedantic -Dasm=__asm -Wall -Wpointer-arith -Wundef    -I../.. -I../../exports/include   -DCSRG_BASED  -DFUNCPROTO=15 -DNARROWPROTO -DXTHREADS  -D_REENTRANT -D_THREAD_SAFE -DXUSE_MTSAFE_API -DXNO_MTSAFE_PWDAPI    -DMALLOC_0_RETURNS_NULL  -DHAS_SNPRINTF -DLIBX11                       -DPOSTLOCALELIBDIR=\"lib\" -I../../../nxcomp -I../../../nxcompext -I/usr/local/include -DNX_CLEAN_ALLOC                  -DNX_CLEAN_GET                    -DNX_CLEAN_FLUSH                  -DNX_CLEAN_SEND                   -DNX_CLEAN_IMAGES                                                   -DNX_IMAGE_SPLIT                  -DNX_IMAGE_MASK                   -DNX_IMAGE_FRAME                                                    -DNX_TRANS_SOCKET                 -DNX_TRANS_PROCESS                                                  -DNX_TRANS_INCLUDE=\"NX.h\"   util/makekeys.c -L/usr/X11R6/lib -lc_r   -Wl,-rpath,/usr/X11R6/lib
/usr/bin/ld: cannot find -lc_r
*** Error code 1 (ignored)
./makekeys < ../../exports/include/X11/keysymdef.h > ks_tables_h
./makekeys: not found
*** Error code 127

Stop in /usr/ports/net/nxserver/work/nx-X11/lib/X11.
*** Error code 1

Stop in /usr/ports/net/nxserver/work/nx-X11/lib.
*** Error code 1

Stop in /usr/ports/net/nxserver/work/nx-X11.
*** Error code 1

Stop in /usr/ports/net/nxserver/work/nx-X11.
** Command failed [exit code 1]: /usr/bin/script -qa /tmp/portinstall.98186.0 env make
** Fix the problem and try again.
** Listing the failed packages (*:skipped / !:failed)
        ! net/nxserver  (missing header)
--->  Packages processed: 0 done, 0 ignored, 0 skipped and 1 failed