sstate.bbclass: fixup extra hardcoded paths

sstate.bbclass: fixup extra hardcoded paths

sstate has a logic to fixup hardcoded paths in scripts,
but it misses in some specific cases, so add
EXTRA_STAGING_FIXMES to the fixup hardcoded paths
mechanism, so that we can specify what hardcoded paths
need to be fixed in a recipe, e.g.
EXTRA_STAGING_FIXMES = "STAGING_BINDIR_TOOLCHAIN"

Signed-off-by: Jackie Huang <jackie.huang@windriver.com>
Signed-off-by: Saul Wold <sgw@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>