Seen in recent bulk, libdispatch was junked during build at this time:

------
cc EOCustomValues.m -c \
      -MMD -MP -I/usr/local/include/gnustep -pipe -Wall -Wno-protocol -Wall -DGDL_MAJOR_VERSION=6 -DGDL_MINOR_VERSION=0 -DGDL_SUBMINOR_VERSION=63 -DSOPE_MAJOR_VERSION=4 -DSOPE_MINOR_VERSION=9 -DSOPE_SUBMINOR_VERSION= -DCGS_LIBDIR_NAME=\@\
"lib\" -DGNUSTEP -DGNUSTEP_BASE_LIBRARY=1 -DGNUSTEP_RUNTIME=1 -D_NONFRAGILE_ABI=1 -DGNUSTEP_BASE_LIBRARY=1 -fno-strict-aliasing -fexceptions -fobjc-exceptions -D_NATIVE_OBJC_EXCEPTIONS -pthread -fPIC -Wall -DGSWARN -DGSDIAGNOSE -Wno-impor
t -O2 -pipe -fobjc-runtime=gnustep-2.2 -fblocks -Wuninitialized -g -frecord-gcc-switches -fconstant-string-class=NSConstantString -I.. -I"../.."/sope-xml -I"../.."/sope-core -I"../.."/sope-core/NGExtensions -I. -I.. -I./FoundationExt -I..
/../sope-core/ -I../../sope-core/NGExtensions/ -I. -I/SOPE-5.11.0_writes_to_HOME/GNUstep/Library/Headers -I/usr/local/include -I/usr/local/include \
       -o obj/libGDLAccess.obj/EOCustomValues.m.o
In file included from EOCustomValues.m:29:
In file included from ./common.h:43:
In file included from /usr/local/include/Foundation/Foundation.h:200:
/usr/local/include/dispatch/dispatch.h:74:10: fatal error: 'dispatch/data.h' file not found
#include <dispatch/data.h>
         ^~~~~~~~~~~~~~~~~
1 error generated.
gmake[5]: *** [/usr/local/share/GNUstep/Makefiles/rules.make:534: obj/libGDLAccess.obj/EOCustomValues.m.o] Error 1
------

/usr/local/include/Foundation/Foundation.h:
195 #ifdef __has_include
196 #  if __has_include(<CoreFoundation/CoreFoundation.h>)
197 #    include <CoreFoundation/CoreFoundation.h>
198 #  endif
199 #  if __has_include(<dispatch/dispatch.h>)
200 #    include <dispatch/dispatch.h>
201 #  endif
202 #endif

I don't suppose there's any real way around this other than either
using DPB_PROPERTIES=nojunk on ports pulling in gnustep, or adding a
dep on libdispatch (perhaps an rdep in gnustep-base)..