cmake: in SDK use OE env var to set default toolchain

Patch the location in cmake where the toolchain file is loaded
to use the (new) OE_CMAKE_TOOLCHAIN_FILE variable to select a default
toolchain if no toolchain has been specified. The cmake alias is
removed.

The alternatives:

 - shell alias fails when cmake is called indirectly (ex: a makefile
   managing several projects which calls cmake for some of them)
   because aliases are not inherited

 - wrapper script that unconditionally adds "-D..." breaks cmake's
   build tests and many other things as it causes cmake to believe it
   should be configuring things when it should not be. For example,
   `cmake -DCMAKE_TOOLCHAIN_FILE=... --build .` does not work (note
   that this also breaks people directly using `cmake --build .` with
   the current alias).

(From OE-Core rev: da60be3768e7183794d63548166d107dbd0a4973)

Signed-off-by: Cody P Schafer <dev@codyps.com>
Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

0 files changed, 0 insertions, 0 deletions