x86-64: Add tests for -z separate-code -z max-page-size=0x1000

	PR ld/22393
	* testsuite/ld-x86-64/pr22393-3a.c: New file.
	* testsuite/ld-x86-64/pr22393-3a.rd: Likewise.
	* testsuite/ld-x86-64/pr22393-3b.c: Likewise.
	* testsuite/ld-x86-64/pr22393-3b.rd: Likewise.
	* testsuite/ld-x86-64/x86-64.exp: Run tests for -z separate-code
	-z max-page-size=0x1000.