1. On SuperH, configuring GCC with explicit variant of the CPU
(like "sh4") limits the default set of multilibs to just that CPU
and requires --with-multilib-list to change. Allow for "unspecified"
variant, so that we can defer to GCC to determine the list.
2. Support toolchains with both endiannesses at the same time.
3. Add a SuperH/newlib sample
4. Add more flags processing for uClibc
Signed-off-by: Alexey Neyman <stilor@att.net>