make.conf:
MYFLAGS=" -D_FORTIFY_SOURCE=2 -D_GLIBCXX_ASSERTIONS -fident -mno-unaligned-access -Wformat -Wformat-security -Werror=format-security -fPIC -fPIE -fcf-protection -fexceptions -fno-short-enums -fomit-frame-pointer -fstrict-aliasing -fstack-protector-all -fstack-protector -fstack-protector-strong -fstack-clash-protection -O2 -pipe "
CFLAGS+="${MYFLAGS}"
CXXFLAGS+="${MYFLAGS}"

Compilation fails with log,
[00:06:42]  cc -DHAVE_CONFIG_H -I. -I. -I../../../include -I../../../include -I./../dpexec -I/wrkdirs/usr/ports/graphics/opendx/work/dx-4.4.4/include -Dfreebsd -O2 -pipe -D_FORTIFY_SOURCE=2 -D_GLIBCXX_ASSERTIONS -fident -mno-unaligned-access -Wformat -Wformat-security -Werror=format-security -fPIC -fPIE -fcf-protection -fexceptions -fno-short-enums -fomit-frame-pointer -fstrict-aliasing -fstack-protector-all -fstack-protector -fstack-protector-strong -fstack-clash-protection -O2 -pipe -march=ivybridge -fstack-protector-strong -fno-strict-aliasing -D_FORTIFY_SOURCE=2 -D_GLIBCXX_ASSERTIONS -fident -mno-unaligned-access -Wformat -Wformat-security -Werror=format-security -fPIC -fPIE -fcf-protection -fexceptions -fno-short-enums -fomit-frame-pointer -fstrict-aliasing -fstack-protector-all -fstack-protector -fstack-protector-strong -fstack-clash-protection -O2 -pipe -I/usr/local/include -I/usr/local/include -O2 -pipe -D_FORTIFY_SOURCE=2 -D_GLIBCXX_ASSERTIONS -fident -mno-unaligned-access -Wformat -Wformat-security -Werror=format-security -fPIC -fPIE -fcf-protection -fexceptions -fno-short-enums -fomit-frame-pointer -fstrict-aliasing -fstack-protector-all -fstack-protector -fstack-protector-strong -fstack-clash-protection -O2 -pipe -march=ivybridge -fstack-protector-strong -fno-strict-aliasing -I/usr/local/include -D_GNU_SOURCE -c colormap.c  -fPIC -DPIC -o .libs/colormap.o
[00:06:42] cc: warning: argument unused during compilation: '-mno-unaligned-access' [-Wunused-command-line-argument]
[00:06:42] cc: warning: argument unused during compilation: '-mno-unaligned-access' [-Wunused-command-line-argument]
[00:06:42] cc: warning: argument unused during compilation: '-mno-unaligned-access' [-Wunused-command-line-argument]
[00:06:42] colormap.c:1170:21: error: format string is not a string literal (potentially insecure) [-Werror,-Wformat-security]
[00:06:42]       sprintf(ei.mp,name);  while(*ei.mp) ei.mp++;
[00:06:42]                     ^~~~
[00:06:42] colormap.c:1170:21: note: treat the string as an argument to avoid this
[00:06:42]       sprintf(ei.mp,name);  while(*ei.mp) ei.mp++;
[00:06:42]                     ^
[00:06:42]                     "%s", 
[00:06:42] colormap.c:1189:18: error: format string is not a string literal (potentially insecure) [-Werror,-Wformat-security]
[00:06:42]    sprintf(ei.mp,name); while(*ei.mp) ei.mp++;
[00:06:42]                  ^~~~
[00:06:42] colormap.c:1189:18: note: treat the string as an argument to avoid this
[00:06:42]    sprintf(ei.mp,name); while(*ei.mp) ei.mp++;
[00:06:42]                  ^
[00:06:42]                  "%s", 
[00:06:42] 2 errors generated.
[00:06:42] gmake[5]: *** [Makefile:459: colormap.lo] Error 1
[00:06:42] gmake[5]: Leaving directory '/wrkdirs/usr/ports/graphics/opendx/work/dx-4.4.4/src/exec/dxmods'
[00:06:42] gmake[4]: *** [Makefile:393: all] Error 2
[00:06:42] gmake[4]: Leaving directory '/wrkdirs/usr/ports/graphics/opendx/work/dx-4.4.4/src/exec/dxmods'
[00:06:42] gmake[3]: *** [Makefile:386: all-recursive] Error 1
[00:06:42] gmake[3]: Leaving directory '/wrkdirs/usr/ports/graphics/opendx/work/dx-4.4.4/src/exec'
[00:06:42] gmake[2]: *** [Makefile:256: all-recursive] Error 1
[00:06:42] gmake[2]: Leaving directory '/wrkdirs/usr/ports/graphics/opendx/work/dx-4.4.4/src'
[00:06:42] gmake[1]: *** [Makefile:277: all-recursive] Error 1
[00:06:42] gmake[1]: Leaving directory '/wrkdirs/usr/ports/graphics/opendx/work/dx-4.4.4'
[00:06:42] *** Error code 1
[00:06:42] 
[00:06:42] Stop.
[00:06:42] make: stopped in /usr/ports/graphics/opendx