Error on PPC64

[dinosaure]

opam-ci got an error on tests with the ppc64 architecture, this is the trace:

# __V=1 /home/opam/.opam/4.13/.opam-switch/build/solo5.0.7.1/toolchain/bin/ppc64le-solo5-none-static-cc  -std=c11 -Wall -Wextra -Werror -O2 -g -c test_tls.c -o test_tls.o
# + exec cc -nostdinc -mstack-protector-guard=global -isystem /home/opam/.opam/4.13/.opam-switch/build/solo5.0.7.1/toolchain/bin/../include/ppc64le-solo5-none-static -I /home/opam/.opam/4.13/.opam-switch/build/solo5.0.7.1/toolchain/bin/../include/solo5 -ffreestanding -fstack-protector-strong -std=c11 -Wall -Wextra -Werror -O2 -g -c test_tls.c -o test_tls.o
# test_tls.c: In function 'solo5_app_main':
# test_tls.c:96:35: error: array subscript 3584 is outside array bounds of 'struct tcb[1]' [-Werror=array-bounds]
#    96 |     tcb1.tp = (void *)&tcb1._data + PPC64_TLS_OFFSET;
#       |                                   ^
# test_tls.c:71:12: note: while referencing 'tcb1'
#    71 | struct tcb tcb1;
#       |            ^~~~
# test_tls.c:97:35: error: array subscript 3584 is outside array bounds of 'struct tcb[1]' [-Werror=array-bounds]
#    97 |     tcb2.tp = (void *)&tcb2._data + PPC64_TLS_OFFSET;
#       |                                   ^
# test_tls.c:72:12: note: while referencing 'tcb2'
#    72 | struct tcb tcb2;
#       |            ^~~~
# test_tls.c:96:35: error: array subscript 3584 is outside array bounds of 'struct tcb[1]' [-Werror=array-bounds]
#    96 |     tcb1.tp = (void *)&tcb1._data + PPC64_TLS_OFFSET;
#       |                                   ^
# test_tls.c:71:12: note: while referencing 'tcb1'
#    71 | struct tcb tcb1;
#       |            ^~~~
# cc1: all warnings being treated as errors
# make[2]: *** [../Makefile.tests:38: test_tls.o] Error 1
# make[2]: Leaving directory '/home/opam/.opam/4.13/.opam-switch/build/solo5.0.7.1/tests/test_tls'
# make[1]: *** [GNUmakefile:38: test_tls] Error 2
# make[1]: Leaving directory '/home/opam/.opam/4.13/.opam-switch/build/solo5.0.7.1/tests'
# make: *** [GNUmakefile:76: tests] Error 2

[dinosaure]

I think we can retest this case with #546 and see what happens.