ENH: linalg: use _umath_linalg for eigvals()
ENH: linalg: use _umath_linalg for eigvalsh()
ENH: linalg: use _umath_linalg for eig()
ENH: linalg: use _umath_linalg for eigh()
ENH: linalg: use _umath_linalg for svd()
BUG: core/umath_linalg: ensure FP error status reflects LAPACK error status
TST: linalg: add tests for generalized linalg functions
MAINT: move umath_linalg under numpy/linalg and use the same lapack_lite

Also, link umath_linalg against the system BLAS/LAPACK if available.
MAINT: move gufuncs_linalg_contents.rst to the docstring of the module