libtoolize: source extract-trace rather than fork and execute each call.

libtoolize: source extract-trace rather than fork and execute each call.

Rather than forking and executing a full $SHELL for each macro
extraction, source the script and its dependencies into our
execution space and use the provided func_extract_trace API.
* libtoolize.m4sh: Source extract-trace from an appropriate
directory determined presently by make.
(func_extract_trace): Remove this wrapper.
* Makefile.am (abs_aux_dir): Absolute path to extract-trace
directory.
(configure_edit): Inject abs_aux_dir into uninstalled libtoolize.
(bin_SCRIPTS): Remove libtoolize.
(uninstall-hook): Manually uninstall libtoolize.
(install-data-local): Inject pkgauxdir into installed libtoolize
during installation.

Signed-off-by: Gary V. Vaughan <gary@gnu.org>