package/bdwgc: Fix 'undefined reference to __data_start' linker error on RISC-V

Backport an upstream patch fixing a link issue with libgc.so on RISC-V

riscv64-buildroot-linux-musl/sysroot/usr/lib/libgc.so: undefined reference to `__data_start'

https://gitlab.com/kubu93/buildroot/-/jobs/1229888983



Signed-off-by: Romain Naour <romain.naour@gmail.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>