"indirect call in function, which are not supported by eBPF" (build failing on Debian Bookworm 12.5.0)

I installed libbpf-dev (without which the build failed because of not finding bpf/bpf_helpers.h)

./configure BPFC=bpf-gcc BPFLD=bpf-ld
make BPFC=bpf-gcc BPFLD=bpf-ld

It successfully compiles quite a bit of c, but eventually runs into this eBPF limitation about indirect calls:

CC: libproc/elfish_32.c
CC: libproc/Psymtab.c
CC: libproc/rtld_db.c
CC: libproc/rtld_offsets.c
CC: libproc/wrap.c
CC: libproc/isadep_dispatch.c
CC: libproc/i386/isadep.c
BUILD-AR: libproc.a
CC: test/triggers/libproc-dlmlib.c
BUILD-AR: libproc-dlmlib.a
CC: test/triggers/libproc-lookup-victim-lib.c
BUILD-AR: libproc-lookup-victim-lib.a
AR: libcommon.a
AR: libport.a
AR: libproc.a
SHLINK: libdtrace.so
SHLINK: libproc-dlmlib.so
SHLINK: libproc-lookup-victim-lib.so
bpf/get_bvar.c: In function ‘dt_get_bvar’:
bpf/get_bvar.c:212:1: error: indirect call in function, which are not supported by eBPF
  212 | }
      | ^
bpf/get_bvar.c:212:1: error: indirect call in function, which are not supported by eBPF
BPF-CC: bpf/agg_lqbin.c
BPF-CC: bpf/agg_qbin.c
BPF-CC: bpf/basename.S
BPF-CC: bpf/cleanpath.S
BPF-CC: bpf/dirname.S
BPF-CC: bpf/get_agg.c
bpf/get_agg.c: In function ‘dt_no_agg’:
bpf/get_agg.c:33:1: error: indirect call in function, which are not supported by eBPF
   33 | }
      | ^
make: *** [Makerules:23: /home/blake/try/dtrace-utils/build/bpf--get_agg.o] Error 1

I tried this with the latest commit in devel and also with the tag 2.0.1.1 with the same result.

Any guidance would be appreciated.

Reproduce the failure on Debian Bookworm with libbpf-dev using the reported configure and make commands. Start with bpf/get_bvar.c and bpf/get_agg.c, then determine why their builds produce unsupported indirect calls; done means the reported build completes past these errors.