gnulib-tool: Drop workarounds for Automake < 1.14. Reported by Collin Funk in <https://lists.gnu.org/archive/html/bug-gnulib/2024-03/msg00384.html>. * gnulib-tool.sh (func_emit_lib_Makefile_am): Emit pkgdata_DATA initialization always. (func_emit_tests_Makefile_am): Likewise. (func_import): Don't emit 'AC_REQUIRE([AM_PROG_CC_C_O])' into gnulib-comp.m4. (func_create_testdir): Don't emit AM_PROG_CC_C_O into configure.ac. Bump required Automake version to 1.14. (func_create_megatestdir): Bump required Automake version to 1.14. * pygnulib/constants.py: Update comments. * pygnulib/GLEmiter.py (GLEmiter.lib_Makefile_am): Emit pkgdata_DATA initialization always. Don't return uses_subdirs. (GLEmiter.tests_Makefile_am): Likewise. * pygnulib/GLImport.py (GLImport.gnulib_comp): Don't emit 'AC_REQUIRE([AM_PROG_CC_C_O])'. (GLImport.execute): Update. * pygnulib/GLTestDir.py (GLTestDir.execute): Don't emit AM_PROG_CC_C_O into configure.ac. Bump required Automake version to 1.14. (GLMegaTestDir.execute): Bump required Automake version to 1.14.