toolchain-scripts/meta-environment: Further cleanup code duplication
There was still duplicated code in toolchain-scripts, this further cleans
up the functions to remove it. The now unused includedir parameter is also
dropped.
The final scripts do end up reordered slightly and the sysroot is parametrised
for the IDE scripts which is an improvement but should have no functional
difference.
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
