Some APIs need libgcc.a.

Signed-off-by: gogojesse <gogojesseco@gmail.com>
Enable CPU L1 ICache and DCache

Signed-off-by: gogojesse <gogojesseco@gmail.com>
Copy non-strip version to libc.a

Signed-off-by: gogojesse <gogojesseco@gmail.com>
Some newlib C APIs need libgcc.a. Accept input customized libgcc.a

Signed-off-by: gogojesse <gogojesseco@gmail.com>