amdgcn: Handle early debug info in mkoffload

amdgcn: Handle early debug info in mkoffload

Forward the early debug information from the input LTO file to the output
HSACO file, in the same way lto-wrapper does.  This is a little more
complicated, however, because the ELF file containing the debug needs to be
converted from x86_64 to amdgcn, and because the offloaded code will have less
content than the host program the debug info describes.

gcc/ChangeLog:

	* config/gcn/mkoffload.c: Include simple-object.h and elf.h.
	(EM_AMDGPU): New macro.
	(ELFOSABI_AMDGPU_HSA): New macro.
	(ELFABIVERSION_AMDGPU_HSA): New macro.
	(EF_AMDGPU_MACH_AMDGCN_GFX803): New macro.
	(EF_AMDGPU_MACH_AMDGCN_GFX900): New macro.
	(EF_AMDGPU_MACH_AMDGCN_GFX906): New macro.
	(R_AMDGPU_NONE): New macro.
	(R_AMDGPU_ABS32_LO): New macro.
	(R_AMDGPU_ABS32_HI): New macro.
	(R_AMDGPU_ABS64): New macro.
	(R_AMDGPU_REL32): New macro.
	(R_AMDGPU_REL64): New macro.
	(R_AMDGPU_ABS32): New macro.
	(R_AMDGPU_GOTPCREL): New macro.
	(R_AMDGPU_GOTPCREL32_LO): New macro.
	(R_AMDGPU_GOTPCREL32_HI): New macro.
	(R_AMDGPU_REL32_LO): New macro.
	(R_AMDGPU_REL32_HI): New macro.
	(reserved): New macro.
	(R_AMDGPU_RELATIVE64): New macro.
	(gcn_s1_name): Delete global variable.
	(gcn_s2_name): Delete global variable.
	(gcn_o_name): Delete global variable.
	(gcn_cfile_name): Delete global variable.
	(files_to_cleanup): New global variable.
	(offload_abi): New global variable.
	(tool_cleanup): Use files_to_cleanup, not explicit list.
	(copy_early_debug_info): New function.
	(main): New local variables gcn_s1_name, gcn_s2_name, gcn_o_name,
	gcn_cfile_name.
	Create files_to_cleanup obstack.
	Recognize -march options.
	Copy early debug info from input .o files.