`find_package(xtensor-blas REQUIRED)` does not expose targets

[david8dixon]

How should user consume xtensor-blas? I discovered that there is an xtensor_blas_INCLUDE_DIRS that I can use to populate targets in my library via target_include_dirs but I would prefer to simply use target_link_libraries(mylib <LINKAGE> xtensor_blas).

[SylvainCorlay]

Indeee it appears that xtensor-blas' cmake is not quite at the same level as the rest of the xtensor stack. We should be exposing targets here. Thanks for the heads up!

[wolfv]

One problem is that we probably don't want to specify which BLAS library to link against from the xtensor-blas target. So that the user can easily override it.

[SylvainCorlay]

Although exportibg xtensor, xtl, xtensor-blas would probably make sense.

[cemoktra]

At least add PARENT_SCOPE to set(XTENSOR_BLAS_INCLUDE_DIR ${INCLUDE_DIR}) so the include dirs are exposed