Details:
- Added bli_4m.c (and header), which defines a simple API that can be
used to query, enable, and disable 4m-based complex support in BLIS.
The macros BLIS_ENABLE_?COMPLEX_VIA_4M are now used to initialize
the variable that determines the state (enabled or disabled).
- Changed bli_info*() API so that all cache and register blocksize-
related query routines return the blksz_t objects' values as they
exist at runtime, rather than return the values as determined by the
configuration system (e.g. bli_kernel.h, or defaults for those values
not specified). This sets the foundation for being able to change
those blocksizes at runtime.