R600: Add stack size to .AMDGPUcsdata section

reviewed-by: Vincent Lejeune <vljn at ovi.com>
R600: Add wavefront size property to the subtargets v2

v2:
  - Initialize wavefront size to 0

reviewed-by: Vincent Lejeune <vljn at ovi.com>
R600: CF_PUSH is the same on Evergreen and Cayman

reviewed-by: Vincent Lejeune <vljn at ovi.com>
R600: Refactor stack size calculation

reviewed-by: Vincent Lejeune <vljn at ovi.com>
R600: Add some missing CF instruction definitions to the .td files.

reviewed-by: Vincent Lejeune <vljn at ovi.com>
R600: Add work-around for the CF stack entry HW bug

The CF stack can be corrupted if you use CF_ALU_PUSH_BEFORE,
CF_ALU_ELSE_AFTER, CF_ALU_BREAK, or CF_ALU_CONTINUE when the number of
sub-entries on the stack is greater than or equal to the stack entry
size and sub-entries modulo 4 is either 0 or 3 (on cedar the bug is
present when number of sub-entries module 8 is either 7 or 0)

We choose to be conservative and always apply the work-around when the
number of sub-enries is greater than or equal to the stack entry size,
so that we can safely over-allocate the stack when we are unsure of the
stack allocation rules.

reviewed-by: Vincent Lejeune <vljn at ovi.com>