ld: add support of QNX stack arguments for aarch64nto

ld: add support of QNX stack arguments for aarch64nto

QNX is handling the stack argument using a .note section. Generate it
according to ELF argument -zexecstack, -zstack-size and a new NTO
argument --lazy-stack. Another NTO argument --stack mimicking
-zstack-size is added in order to ensure compatibility with previously
made NTO linkers.
This requires a new emultempl nto.em which is applied above the default
${ARCH}elf.em.

ld/ChangeLog:

	* emulparams/aarch64nto.sh: Move to nto.em.
	* emultempl/nto.em: New file.
	* testsuite/ld-aarch64/aarch64-nto.exp: New test.
	* testsuite/ld-aarch64/nto-stack-note-1.d: New test.
	* testsuite/ld-aarch64/nto-stack-note-2.d: New test.
	* testsuite/ld-aarch64/start.s: New test.