Added support for pre-broadcast when packing B.

Details:
- Added support for being able to duplicate (broadcast) elements in
  memory when packing matrix B (ie: the left-hand operand) in level-3
  operations. This turns out advantageous for some architectures that
  can afford the cost of the extra bandwidth and somehow benefit from
  the pre-broadcast elements (and thus being able to avoid using
  broadcast-style load instructions on micro-rows of B in the gemm
  microkernel).
- Support optionally disabling right-side hemm and symm. If this occurs,
  hemm_r is implemented in terms of hemm_l (and symm_r in terms of
  symm_l). This is needed when broadcasting during packing because the
  alternative--supporting the broadcast of B while also allowing matrix
  B to be Hermitian/symmetric--would be an absolute mess.
- Support alignment factors for packed blocks of A, B, and C separately
  (as well as for general-purpose buffers). In addition, we support
  byte offsets from those alignment values (which is different from
  aligning by align+offset bytes to begin with). The default alignment
  values are BLIS_PAGE_SIZE in all four cases, with the offset values
  defaulting to zero.
- Pass pack_t schema into bli_?packm_cxk() so that it can be then passed
  into the packm kernel, where it will be needed by packm kernels that
  perform broadcasts of B, since the idea is that we *only* want to
  broadcast when packing micropanels of B and not A.
- Added definition for variadic bli_cntx_set_l3_vir_ukrs(), which can be
  used to set custom virtual level-3 microkernels in the cntx_t, which
  would typically be done in the bli_cntx_init_*() function defined in
  the subconfiguration of interest.
- Added a "broadcast B" kernel function for use with NP/NR = 12/6,
  defined in in ref_kernels/1m/bli_packm_cxk_bb_ref.c.
- Added a gemm, gemmtrsm, and trsm "broadcast B" reference kernels
  defined in ref_kernels/3/bb. (These kernels have been tested with
  double real with NP/NR = 12/6.)
- Added #ifndef ... #endif guards around several macro constants defined
  in frame/include/bli_kernel_macro_defs.h.
- Defined a few "broadcast B" static functions in
  frame/include/level0/bb for use by "broadcast B"-style packm reference
  kernels. For now, only the real domain kernels are tested and fully
  defined.
- Output the alignment and offset values for packed blocks of A and B
  in the testsuite's "BLIS configuration info" section.
- Comment updates to various files.
- Bumped so_version to 3.0.0.

frame/include/bli_kernel_macro_defs.h

@@ -165,19 +165,56 @@
 
 // Alignment size used to align local stack buffers within macro-kernel
 // functions.
+#ifndef BLIS_STACK_BUF_ALIGN_SIZE
 #define BLIS_STACK_BUF_ALIGN_SIZE        BLIS_SIMD_ALIGN_SIZE
+#endif
 
 // Alignment size used when allocating memory via BLIS_MALLOC_USER.
 // To disable heap alignment, set this to 1.
+#ifndef BLIS_HEAP_ADDR_ALIGN_SIZE
 #define BLIS_HEAP_ADDR_ALIGN_SIZE        BLIS_SIMD_ALIGN_SIZE
+#endif
 
 // Alignment size used when sizing leading dimensions of memory allocated
 // via BLIS_MALLOC_USER.
+#ifndef BLIS_HEAP_STRIDE_ALIGN_SIZE
 #define BLIS_HEAP_STRIDE_ALIGN_SIZE      BLIS_SIMD_ALIGN_SIZE
+#endif
 
-// Alignment size used when allocating blocks to the internal memory
+// Alignment sizes used when allocating blocks to the internal memory
 // pool, via BLIS_MALLOC_POOL.
-#define BLIS_POOL_ADDR_ALIGN_SIZE        BLIS_PAGE_SIZE
+#ifndef BLIS_POOL_ADDR_ALIGN_SIZE_A
+#define BLIS_POOL_ADDR_ALIGN_SIZE_A      BLIS_PAGE_SIZE
+#endif
+
+#ifndef BLIS_POOL_ADDR_ALIGN_SIZE_B
+#define BLIS_POOL_ADDR_ALIGN_SIZE_B      BLIS_PAGE_SIZE
+#endif
+
+#ifndef BLIS_POOL_ADDR_ALIGN_SIZE_C
+#define BLIS_POOL_ADDR_ALIGN_SIZE_C      BLIS_PAGE_SIZE
+#endif
+
+#ifndef BLIS_POOL_ADDR_ALIGN_SIZE_GEN
+#define BLIS_POOL_ADDR_ALIGN_SIZE_GEN    BLIS_PAGE_SIZE
+#endif
+
+// Offsets from alignment specified by BLIS_POOL_ADDR_ALIGN_SIZE_*.
+#ifndef BLIS_POOL_ADDR_OFFSET_SIZE_A
+#define BLIS_POOL_ADDR_OFFSET_SIZE_A     0
+#endif
+
+#ifndef BLIS_POOL_ADDR_OFFSET_SIZE_B
+#define BLIS_POOL_ADDR_OFFSET_SIZE_B     0
+#endif
+
+#ifndef BLIS_POOL_ADDR_OFFSET_SIZE_C
+#define BLIS_POOL_ADDR_OFFSET_SIZE_C     0
+#endif
+
+#ifndef BLIS_POOL_ADDR_OFFSET_SIZE_GEN
+#define BLIS_POOL_ADDR_OFFSET_SIZE_GEN   0
+#endif