find: fix -L and -delete removing symlinks to directories Fixes https://savannah.gnu.org/bugs/?46305
* NEWS (Bug Fixes): Mention the change. * doc/find.texi (-delete action): Add explanation of the issue. * find/find.1 (-delete action): Add explanation of the issue. * find/pred.c (pred_delete): Do unlink when rmdir fails (ENOTDIR). * find/testsuite/Makefile.am: Add new test and output files. * find/testsuite/find.gnu/deletedirsymlink.exp: New test. * find/testsuite/find.gnu/deletedirsymlink.xo: New test output.