This ensures that abort message is actually visible to the user.

libgcc for boot environment isn't always present and compatible.
libgcc is often absent if endianness or bit-size at boot is different
from running OS.
libgcc may use optimised opcodes that aren't available on boot time.
So instead of relying on libgcc shipped with the compiler, supply
the functions in GRUB directly.
Tests are present to ensure that those replacement functions behave the
way compiler expects them to.

Previously we supplied only unsigned divisions on platforms that need software
division.
Yet compiler may itself use a signed division. A typical example would be a
difference between 2 pointers which involves division by object size.

Fixes ARM compilation

	Reported by: Yves Blusseau <blusseau@zetam.org>.

	using not very significant $target_os.

	A bit tricky because this function has to continue to work without
	heap for short strings. Fixing prealloc to 32 arguments is reasonable
	but make all stack references use 32-bit offset rather than 8-bit one.
	So split va_args preparsing to separate function and put the prealloc
	into the caller.

	Export abort () when compiling with clang.

	On upcoming arm64 port libgcc ctz* are not usable in standalone
	environment. Since we need ctz* for this case and implementation is
	in C we may as well use it on all concerned platforms.

GRUB_UTIL case.
* include/grub/misc.h: Likewise.

	* grub-core/kern/misc.c (__bzero) [__APPLE__]: New function.

	simple division on arm and ia64.

	* conf/Makefile.common (CFLAGS_PLATFORM): Don't add -mrtd -mregparm=3
	unconditionally.
	* configure.ac: Add -no-integrated-as when using clangfor asm files.
	Add -mrtd -mregparm=3 on i386 when not using clang.
	* grub-core/kern/misc.c (grub_memset): Add volatile when on clang.

	strncpy.
	* grub-core/fs/jfs.c (grub_jfs_lookup_symlink): Likewise.
	* grub-core/kern/misc.c (grub_strncpy): Move from here ...
	* include/grub/misc.h (grub_strncpy): ... to here. Make inline.
	* grub-core/net/net.c (grub_net_addr_to_str): Use COMPILE_TIME_ASSERT
	+ strcpy rather than strncpy.

	handling.

	transform invalid unicode codepoints.

	\0 checking.

	\0 checking.

	Saves 70 bytes on compressed image.

	check.

	Saves 10 bytes on compressed image.

	* include/grub/misc.h (grub_isprint): ... here. Make inline.

	Saves 20 bytes on compressed image due to remving exporting.

	"(null)" string.
	Simplify expressions to save around 256 bytes in kernel.img.
	* tests/printf_unit_test.c (printf_test): Add "(null)" tests.

	shadowing.
	* grub-core/kern/disk.c: Likewise.
	* grub-core/kern/misc.c: Likewise.
	* include/grub/parser.h: Likewise.
	* include/grub/script_sh.h: Likewise.
	* include/grub/zfs/zfs.h: Likewise.

	* tests/printf_unit_test.c (printf_test): Add %% tests.
	Reported by: Paulo Flabiano Smorigo.

	present. Remove symbols used for trampolines to make
	link fail if trampolines are present.

* grub-core/kern/misc.c (grub_vsnprintf_real): Parse '-', '.', and
'$' in the correct order when collecting type information.

	* grub-core/kern/misc.c: Likewise.
	* grub-core/loader/i386/xnu.c: Likewise.
	* include/grub/i386/tsc.h: Likewise.
	* include/grub/symbol.h: Likewise.

	(memmove) [__APPLE__]: Likewise.
	(memcpy) [__APPLE__]: Likewise.
	(memset) [__APPLE__]: Likewise.
	* grub-core/kern/misc.c (memcmp) [__APPLE__]: Likewise.
	(memmove) [__APPLE__]: Likewise.
	(memcpy) [__APPLE__]: Likewise.
	(memset) [__APPLE__]: Likewise.

	per common usage and preffered in several parts of code.
	(grub_memcmp): Likewise.
	(grub_strncmp): Likewise.
	* include/grub/misc.h (grub_strcasecmp): Likewise.
	(grub_strncasecmp): Likewise.
	* Makefile.util.def (cmp_test): New test.
	(grub_script_strcmp): Likewise.
	* tests/cmp_unit_test.c: New file.
	* tests/grub_script_strcmp.in: Likewise.
	* grub-core/fs/hfsplus.c (grub_hfsplus_cmp_catkey): Add a comment.

	resulted in leak of arguments.

	* include/grub/misc.h (grub_stpcpy): ... to here. Inlined.

	checks which are always false on some platforms.
	(grub_cmd_lsacpi): Likewise.
	* grub-core/kern/misc.c (grub_strtoul): Likewise.
	* grub-core/loader/multiboot.c (grub_multiboot_set_video_mode):
	Likewise.

	* tests/printf_unit_test.c: New file.
	* Makefile.util.def (printf_test): New test.
	* grub-core/kern/misc.c (grub_vsnprintf_real): Support %1$d syntax.