Don't generate undefined variable warnings for variables that are
internal / special to make and where the empty string is valid.
Rather than defining them to empty, which could introduce unwanted
behavior, keep a list of variable names which we should never warn
about.
* src/variable.h (warn_undefined): Convert the macro to a function.
* src/variable.c (defined_vars): Always "defined" variable names.
(warn_undefined): Implement as a function and check against the
defined_vars before generating a warning.
* src/read.c (read_all_makefiles): No need to reset warning flag.
* src/vpath.c (build_vpath_lists): Ditto.
* tests/scripts/options/warn-undefined-variables: Expand all the
pre-defined variables to ensure warnings are not generated.
* src/makeint.h (stpcpy): Add missing declaration.
* src/amiga.c (MyExecute): Avoid extra strlen using stpcpy.
* src/function.c (func_shell_base): Ditto.
(func_error): Use memcpy() not strcpy() when we know the length.
* src/job.c (construct_command_argv_internal): Use stpcpy().
* src/main.c (main): Ditto.
(define_makeflags): Ditto.
* src/variable.c (print_target_variables): Use memcpy() when we know
the length.
* src/commands.c (set_file_variables): Use mempcpy().
* src/expand.c (variable_buffer_output): Ditto.
* src/file.c (expand_deps): Ditto.
* src/function.c (abspath): Ditto.
(handle_function): Ditto.
* src/implicit.c (pattern_search): Ditto.
* src/job.c (construct_command_argv_internal): Use mempcpy() and
don't add multiple spaces when there are no shell flags.
* src/main.c (decode_env_switches): Use mempcpy() to simplify.
(define_makeflags): Ditto.
* src/variable.c (selective_vpath_search): Ditto.
* build_w32.bat: Quote uses of %VSWHERE% so it can contain spaces
* src/hash.c (hash_init): Avoid use of an undefined struct.
(hash_rehash): Ditto.
* src/vpath.c (construct_vpath_list): Cast explicitly to void*.
Move the source code (other than glob) into the "src" subdirectory.
Update all scripting and recommendations to support this change.
* *.c, *.h, w32/*: Move to src/
* configure.ac, Makefile.am, maintMakefile: Locate new source files.
* Basic.mk.template, mk/*: Update for new source file locations.
* NEWS, README.DOS.template: Update for new locations.
* build.template, build_w32.bat, builddos.bat: Ditto.
* po/POTFILES.in: Ditto
* tests/run_make_tests.pl, tests/scripts/features/load*: Ditto.
* make.1: Move to doc.
* mk/VMS.mk: Add support for building on VMS (hopefully).
* makefile.vms, prepare_w32.bat: Remove.
* SCOPTIONS: Update to define HAVE_CONFIG_H
