ipa-sra: Check also ECF_LOOPING_CONST_OR_PURE when evaluating calls

ipa-sra: Check also ECF_LOOPING_CONST_OR_PURE when evaluating calls

in PR 103267 Honza found out that IPA-SRA does not look at
ECF_LOOPING_CONST_OR_PURE when evaluating if a call can have side
effects.  Fixed with this patch.  The testcase infinitely loops in a
const function, so it would not make a good addition to the testsuite.

This patch is a manual backport of commit
e5440bc08e07fd491dcccd47e1b86a5985ee117c to the old "early" IPA-SRA.

gcc/ChangeLog:

2021-12-01  Martin Jambor  <mjambor@suse.cz>

	PR ipa/103267
	* tree-sra.c (scan_function): Also check ECF_LOOPING_CONST_OR_PURE
	flag.