aarch64: testsuite: disable stack protector for pr104005.c

Storing stack guarding variable need one stp instruction, breaking the
scan-assembler-not pattern in the test.  Disable stack protector to
avoid a test failure with --enable-default-ssp.

gcc/testsuite/ChangeLog:

	* gcc.target/aarch64/pr104005.c (dg-options): Add
	-fno-stack-protector.