This patch adds implementations of memcpy, memmove, memset and strcmp
optimized for size. The changes have been tested in
riscv/riscv-gnu-toolchain by riscv-dejagnu with
riscv-sim.exp/riscv-sim-nano.exp.
- For prevent confuse about what BSD license variant we used, 2- or
3-clause license, we change the license to FreeBSD license to make
it unambiguously refers to the 2-clause license.
