gnulib-tool.py: Follow gnulib-tool changes, part 27. Follow gnulib-tool changes 2017-03-12 Paul Eggert <eggert@cs.ucla.edu> gnulib-tool: new option --gnu-make 2017-03-13 Paul Eggert <eggert@cs.ucla.edu> gnulib-tool: minor --gnu-make fixups 2017-03-14 Paul Eggert <eggert@cs.ucla.edu> gnulib-tool: fix typo in comment output 2017-05-14 Paul Eggert <eggert@cs.ucla.edu> gnulib-tool: improve GNU Make debugging 2018-07-04 Paul Eggert <eggert@cs.ucla.edu> gnulib-tool: minor tweaks for --gnu-make * gnulib-tool.py (main): Add --gnu-make option. Do not allow --gnu-make in test modes, since they all require Automake. * pygnulib/GLConfig.py: Add gnu_make argument to constructor. (getGnuMake, setGnuMake, resetGnuMake): New methods for accessing the gnu_make instance variable. * pygnulib/GLEmiter.py (GLEmiter.lib_Makefile_am): Use the "+=" operator with GNU Make and Automake. Transform conditionals to GNU Make syntax if --gnu-make is in use. Use a Autoconf subprocess to define values and check the return code for errors. (GLEmiter.tests_Makefile_am): Likewise. * pygnulib/GLImport.py (GLImport.actioncmd): Add "--gnu-make" to the output comment if it is in use. (GLImport.gnulib_comp): Don't require "AM_PROG_CC_C_O" when using GNU Make. * pygnulib/GLInfo.py (GLInfo.usage): Update help message to reflect addition of --gnu-make. * pygnulib/GLModuleSystem.py (GLModuleTable.transitive_closure): Don't add Automake snippets as unconditional dependencies when using --gnu-make.