toolchain: fix dangling symlink to self in FixupLibdir

toolchain: fix dangling symlink to self in FixupLibdir

This avoids a dangling symlink to self when reinstalling the toolchain:

./staging_dir/toolchain-mips_24kc_gcc-9.3.0_musl/lib/lib -> lib

This is caused by the fact that in the toolchain dir we have

'lib64 -> lib'

and on executing

'ln lib ./staging_dir/toolchain-mips_24kc_gcc-9.3.0_musl/lib64'

ln dereference the symbolic link 'lib64' to 'lib' so the REAL command is

'ln lib ./staging_dir/toolchain-mips_24kc_gcc-9.3.0_musl/lib'

this results in the dangling symlink to self.

Signed-off-by: Sven Wegener <sven.wegener@stealer.net>
[ add more details to the commit description and fix title ]
Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>