[AArch64] Define TARGET_FLAGS_REGNUM

Ramana noted:

This defines TARGET_FLAGS_REGNUM for AArch64 to be CC_REGNUM. Noticed
this turns on the cmpelim pass after reload and in a few examples and
a couple of benchmarks I noticed a number of comparisons getting
deleted.

From-SVN: r209643

gcc/ChangeLog

+2014-04-22  Ramana Radhakrishnan  <ramana.radhakrishnan@arm.com>
+
+	* config/aarch64/aarch64.c (TARGET_FLAGS_REGNUM): Define.
+
 2014-04-22  Alex Velenko  <Alex.Velenko@arm.com>
 
 	* config/aarch64/aarch64-builtins.c (TYPES_REINTERP): Removed.

gcc/config/aarch64/aarch64.c

@@ -8512,6 +8512,9 @@ aarch64_cannot_change_mode_class (enum machine_mode from,
 #undef TARGET_FIXED_CONDITION_CODE_REGS
 #define TARGET_FIXED_CONDITION_CODE_REGS aarch64_fixed_condition_code_regs
 
+#undef TARGET_FLAGS_REGNUM
+#define TARGET_FLAGS_REGNUM CC_REGNUM
+
 struct gcc_target targetm = TARGET_INITIALIZER;
 
 #include "gt-aarch64.h"