* libtool.m4 (AC_PROG_LIBTOOL): added --with-pic flag
* ltconfig.in: new pic_mode variable and --prefer[-non]-pic flags,
fixed the strip check (reported by Keith Bostic <bostic@bostic.com>)
* ltmain.in (compile mode): build only PIC/non-PIC code depending
on pic_mode
* libltdl/README: document the supported dlopen interfaces
* doc/libtool.texi (tests): documented new tests
* tests/Makefile.am: added new tests
* tests/demo-pic.test: new test to test --with-pic
* tests/demo-nopic.test: new test to test --without-pic
* tests/build-relink2.test: variant of build-relink.test that
uses depdemo
