Turn of ipa-ra in builtins test (PR91059)

Turn of ipa-ra in builtins test (PR91059)

The gcc.c-torture/execute/builtins/lib directory contains a reimplementation
of many C library string functions, which causes non-trivial register allocation
bugs with LTO and static linked libraries.  To fix this long-standing test
issue, turn off ipa-ra which avoids the register corruption across calls.  All
builtin torture tests now pass on aarch64-none-elf.  Committed as obvious.

    testsuite/
	PR testsuite/91059
	PR testsuite/78529
	* gcc.c-torture/execute/builtins/builtins.exp: Add -fno-ipa-ra.

From-SVN: r273238