Use separate sed expressions to escape auto-load directories.

Use separate sed expressions to escape auto-load directories.

Not all sed implementations support alternation via \| in the default
regular expressions.  Instead, resort to separate sed expressions via
-e for $debugdir and $datadir.  This fixes the default setting of the
auto-load directories on FreeBSD.  Previously on FreeBSD the sed
invocation was a no-op causing the debugdir and datadir values to be
expanded yielding an autoload path of ':${prefix}/share/gdb'.

gdb/ChangeLog:

	* configure: Re-generate.
	* configure.ac: Use separate sed expressions to escape variables
	in auto-load directories.