Add basic support for the Blackfin architecture

For uClibc, the name of the Blackfin architecture is 'bfin'. Actually,
the naming of the architecture is quite messy: for toolchain tuples
and uClibc, it's bfin, but for the kernel, it's blackfin. We've
arbitraly choosen to name it "blackfin" in Crosstool-NG.

Add Blackfin-related uClibc patch to fix a build failure related to
fork() being used in unistd/daemon.c.

Yann E. MORIN:
Apply the patch to the kernel/linux build script to use 'linux'
in the noMMU tuples. See:
http://sourceware.org/ml/crossgcc/2010-04/msg00010.html

 --- binutils/ld/ldmain.c

 +++ binutils/ld/ldmain.c

 @@ -273,2 +273,5 @@ main (int argc, char **argv)

    link_info.emit_hash = TRUE;

 +#ifndef __mips__

 +  link_info.emit_gnu_hash = TRUE;

 +#endif

    link_info.callbacks = &link_callbacks;