.gitlab: re-enable integer-simple substitute (BIGNUM_BACKEND)
Recently build system migrated from INTEGER_LIBRARY to BIGNUM_BACKEND. But gitlab CI was never updated. Let's enable BIGNUM_BACKEND=native.
Bug: #18437 (closed)
Recently build system migrated from INTEGER_LIBRARY to BIGNUM_BACKEND. But gitlab CI was never updated. Let's enable BIGNUM_BACKEND=native.
Bug: #18437 (closed)