[Bug gcov-profile/123019][V3] Fix Virtual SSA ICE

[Bug gcov-profile/123019][V3] Fix Virtual SSA ICE

The bug is a stale Virtual SSA VDEF on calls to functions that have
been marked const or pure.

pure_const pass analyzes function rocksdb::y::y() and determines it has no side
effects and marks it as const.

At this point, existing call sites to y::y() in other functions still have:
   # .MEM_12 = VDEF <.MEM_11>   rocksdb::y::y (&l, _9);
The VDEF indicates the call modifies memory but now that y::y() is const,
this VDEF is stale

Later passes  after feedback_fnsplit SSA verification fails. Added fixup.

gcc/ChangeLog:

2026-01-07  Kugan Vivekanandarajah  <kvivekananda@nvidia.com>

	PR gcov-profile/123019
	* auto-profile.cc (auto_profile): Call execute_fixup_cfg.

Signed-off-by: Kugan Vivekanandarajah <kvivekananda@nvidia.com>