forwprop: Move check of limit first [PR121474]

forwprop: Move check of limit first [PR121474]

This is the first step in handling the review part of:
https://gcc.gnu.org/pipermail/gcc-patches/2025-August/692091.html
'''
Oh, as we now do alias walks in forwprop maybe we should make this
conditional and do
this not for all pass instances, since it makes forwprop possibly a lot slower?
'''

The check of the limit was after the alias check which could slow down things.
This moves the check of the limit to begining of the if.

Bootstrapped and tested on x86_64-linux-gnu.

Pushed as obvious.

	PR tree-optimization/121474
gcc/ChangeLog:

	* tree-ssa-forwprop.cc (optimize_aggr_zeroprop): Move the check
	for limit before the alias check.

Signed-off-by: Andrew Pinski <andrew.pinski@oss.qualcomm.com>