c++tools: Don't check --enable-default-pie.

c++tools: Don't check --enable-default-pie.

`--enable-default-pie` is an option to specify whether to enable
position-independent executables by default for `target`.

However c++tools is build for `host`, so it should just follow
`--enable-host-pie` option to determine whether to build with
position-independent executables or not.

NOTE:

I checked PR 98324 and build with same configure option
(`--enable-default-pie` and lto bootstrap) on x86-64 linux to make sure
it won't cause same problem.

c++tools/ChangeLog:

	* configure.ac: Don't check `--enable-default-pie`.
	* configure: Regen.