When users try to build a cross-compiler without first installing
binutils they get confusing errors like:
/tmp/gcc-obj/./gcc/as: line 114: exec: -m: invalid option

This is an incredibly common source of questions on gcc-help and IRC,
and bogus bug reports e.g. see PR 116119 for the latest example.

This change adds an explicit check for an empty $original variable and
exits with a user-friendly error.

gcc/ChangeLog:

	* exec-tool.in: Exit with an error if $original is empty.

This reverts commit 6124f4248888484f419671f4f7bd40d253d3de06.
It lacks pieces to work with system binutils.

Using the system objcopy is wrong when other configure checks have
probed a different set of binutils (I've noticed the problem on a system
where the base objcopy can't deal with compressed debug sections).
Arrange for the matching one to be picked up, first and foremost if an
"in tree" one is available, by mirroring respective logic already
present for nm.

gcc/

	* Makefile.in (ORIGINAL_OBJCOPY_FOR_TARGET): New.
	* configure.ac: Check for objcopy, producing
	ORIGINAL_OBJCOPY_FOR_TARGET.
	* configure: Update accordingly.
	* exec-tool.in (ORIGINAL_OBJCOPY_FOR_TARGET): New.
	Handle objcopy.

In order to enable DWARF versions > 2 we need a sufficiently modern
version of dsymutil (in addition to the assembler / linker).  This
allows the user to configure a different path from the installed one.

In addition, there are several sources of dsymutil so we differentiate
these in order to be get accurate version information.

Signed-off-by: Iain Sandoe <iain@sandoe.co.uk>

gcc/ChangeLog:

	* configure.ac: Handle --with-dsymutil in the same way as we
	do for the assembler and linker.  (DEFAULT_DSYMUTIL): New.
	Extract the type and version for the dsymutil configured or
	found by the default searches.
	* config.in: Regenerated.
	* configure: Regenerated.
	* collect2.c (do_dsymutil): Handle locating dsymutil in the
	same way as for the assembler and  linker.
	* config/darwin.h (DSYMUTIL): Delete.
	* gcc.c: Report a configured dsymutil correctly.
	* exec-tool.in: Allow for dsymutil.

ChangeLog:

	* Makefile.def: Add dsymutil defs.
	* Makefile.in: Regenerated.
	* Makefile.tpl: Add dsymutil to flags.
	* configure: Regenerated.
	* configure.ac: Add dsymutil to target and build recipes.

From-SVN: r279813