Change the default characteristics of DLLs built by the linker to more secure settings.

Change the default characteristics of DLLs built by the linker to more secure settings.

	PR 19011
	* emultempl/pe.em (DEFAULT_DLL_CHARACTERISTICS): Define.
	(pe_dll_characteristics): Initialise to DEFAULT_DLL_CHARACTERISTICS.
	(add_options): Add options to disable DLL characteristics.
	(list_options): List the new options.
	(handle_options): Handle the new options.
	* emultempl/pep.em: Similar changes to above.
	(NT_EXE_IMAGE_BASE): Default to an address above 4G.
	(NT_DLL_IMAGE_BASE, NT_DLL_AUTO_IMAGE_BASE,
	(NT_DLL_AUTO_IMAGE_MASK): Likewise.
	* ld.texi: Document the new options.
	* pe-dll.c (pe_dll_enable_reloc_section): Change to default to
	true.
	(generate_reloc): Do nothing if there is no reloc section.
	(pe_exe_fill_sections): Only assign the reloc section contents if
	the section exists.
	* testsuite/ld-pe/pe.exp: Add the --disable-reloc-section flag to
	the .secrel32 tests.
	* testsuite/ld-scripts/provide-8.d: Expect for fail on PE targets.
	* NEWS: Mention the change in DLL generation.