Improve dump files for SRA early candidate check v2

Improve dump files for SRA early candidate check v2

v2: Include message improvements from Eric Botcazou

gcc/:
2011-06-24  Andi Kleen  <ak@linux.intel.com>

	* tree-sra.c (type_internals_preclude_sra_p): Add msg
	parameter. Split up ifs and report reason in *msg.
	(reject): Add.
	(find_var_candiate): Add msg variable.
	Split up ifs and report reason to reject.
	(find_param_candidates): Add msg variable.
	Pass msg to type_internals_preclude_sra_p.

From-SVN: r175370