Optimize vertex_shader_uid_data down to 28 bytes

This started as a fixing a misalignment issue, but I got carried away.
Was originally 41 bytes (overflowing it's expected 40 bytes by 1 bit).

Now it's 27 bytes plus 8 bits of padding (ready for future expansion).

The savings come from:
 - Removing UV usage from components, it can be reconstructed from
   texcoord_elem_count (saved 8 bits)
 - Removed the 8 unused bits from texMtxInfo_n_projection (saved 8 bits)
 - Removing unused bit from from start of components (saved 1 bit)
 - Removed extra bit from inputform, texgentype and sourcerow
 - packed texMtxInfo_n_projection and texcoord_elem_count back into
   the per texgen info space freed up above. (saved 24 bits)
 - Overlayed postMtx index and Emboss mode shifts into a union based on
   texgentype (saved 56 bits)
 - Move to a single-bit union tag, freeing up an extra bit for regular
   texgens.
 - Move PotMtx normalize into the freed up space (saved 8 bits)

Total savings: 105 bits of data

EDIT: Even worse, MSVC wasn't respecting pack(1) for bitfields at all,
      so on windows this struct was actually quite a bit larger.
      Something like 80 bytes, if not more.

      Fixed this by dropping the size of any enums used in these
      bit structs to u8. Our Common::BitField allows for the underlying
      type to be explicitly specified to something larger.

      msvc's bitfield packing appears to be completely braindead, can't
      mix sizes at all.

1 files changed, 30 insertions, 28 deletions

diff --git a/Source/Core/VideoCommon/NativeVertexFormat.h b/Source/Core/VideoCommon/NativeVertexFormat.h
index 0f6be25541..76ca7875c2 100644
--- a/Source/Core/VideoCommon/NativeVertexFormat.h
+++ b/Source/Core/VideoCommon/NativeVertexFormat.h
@@ -12,36 +12,38 @@
 // m_components
 enum : u32
 {
-  VB_HAS_POSMTXIDX = (1 << 1),
-  VB_HAS_TEXMTXIDX0 = (1 << 2),
-  VB_HAS_TEXMTXIDX1 = (1 << 3),
-  VB_HAS_TEXMTXIDX2 = (1 << 4),
-  VB_HAS_TEXMTXIDX3 = (1 << 5),
-  VB_HAS_TEXMTXIDX4 = (1 << 6),
-  VB_HAS_TEXMTXIDX5 = (1 << 7),
-  VB_HAS_TEXMTXIDX6 = (1 << 8),
-  VB_HAS_TEXMTXIDX7 = (1 << 9),
-  VB_HAS_TEXMTXIDXALL = (0xff << 2),
+  VB_HAS_TEXMTXIDX0 = (1 << 0),
+  VB_HAS_TEXMTXIDX1 = (1 << 1),
+  VB_HAS_TEXMTXIDX2 = (1 << 2),
+  VB_HAS_TEXMTXIDX3 = (1 << 3),
+  VB_HAS_TEXMTXIDX4 = (1 << 4),
+  VB_HAS_TEXMTXIDX5 = (1 << 5),
+  VB_HAS_TEXMTXIDX6 = (1 << 6),
+  VB_HAS_TEXMTXIDX7 = (1 << 7),
+  VB_HAS_TEXMTXIDXALL = (0xff << 0),
+
+  VB_HAS_POSMTXIDX = (1 << 8),
 
   // VB_HAS_POS=0, // Implied, it always has pos! don't bother testing
-  VB_HAS_NORMAL = (1 << 10),
-  VB_HAS_TANGENT = (1 << 11),
-  VB_HAS_BINORMAL = (1 << 12),
-
-  VB_COL_SHIFT = 13,
-  VB_HAS_COL0 = (1 << 13),
-  VB_HAS_COL1 = (1 << 14),
-
-  VB_HAS_UV0 = (1 << 15),
-  VB_HAS_UV1 = (1 << 16),
-  VB_HAS_UV2 = (1 << 17),
-  VB_HAS_UV3 = (1 << 18),
-  VB_HAS_UV4 = (1 << 19),
-  VB_HAS_UV5 = (1 << 20),
-  VB_HAS_UV6 = (1 << 21),
-  VB_HAS_UV7 = (1 << 22),
-  VB_HAS_UVALL = (0xff << 15),
-  VB_HAS_UVTEXMTXSHIFT = 13,
+  VB_HAS_NORMAL = (1 << 9),
+  VB_HAS_TANGENT = (1 << 10),
+  VB_HAS_BINORMAL = (1 << 11),
+
+  VB_COL_SHIFT = 12,
+  VB_HAS_COL0 = (1 << 12),
+  VB_HAS_COL1 = (1 << 13),
+  VB_HAS_SHARED = 0x3f << 8,
+
+  VB_HAS_UV0 = (1 << 16),
+  VB_HAS_UV1 = (1 << 17),
+  VB_HAS_UV2 = (1 << 18),
+  VB_HAS_UV3 = (1 << 19),
+  VB_HAS_UV4 = (1 << 20),
+  VB_HAS_UV5 = (1 << 21),
+  VB_HAS_UV6 = (1 << 22),
+  VB_HAS_UV7 = (1 << 23),
+  VB_HAS_UVALL = (0xff << 16),
+  VB_HAS_UVTEXMTXSHIFT = 16,
 };
 
 struct AttributeFormat