Simple repro:
$ mkdir build
$ cd build
$ ../configure --enable-benchmark
[...]
$ make
CC src/bench_verify.o
CCLD bench_verify
CC src/bench_sign.o
CCLD bench_sign
CC src/bench_internal-bench_internal.o
In file included from ../src/ecmult_gen_impl.h:15:0,
from ../src/secp256k1.c:16,
from ../src/bench_internal.c:19:
./src/ecmult_static_context.h:3:10: fatal error: group.h: No such file or directory
#include "group.h"
^~~~~~~~~
compilation terminated.
Makefile:1068: recipe for target 'src/bench_internal-bench_internal.o' failed
make: *** [src/bench_internal-bench_internal.o] Error 1