Remove or update warnings related to "conda-build 4.0"

[h-vetinari]

With the recent change to CalVer, conda-build 4.0 isn't going to happen anymore. The warnings referring to it should be updated (or if not relevant anymore, removed).

Found some instances below, though there may be more:

conda-build/conda_build/api.py

Lines 184 to 188 in 9b04330

	log.warn(
	"deprecation warning: this function has been renamed to get_output_file_paths, "
	"to reflect that potentially multiple paths are returned. This function will be "
	"removed in the conda-build 4.0 release."
	)

conda-build/conda_build/windows.py

Lines 108 to 112 in 9b04330

	log.warn(
	"Using legacy MSVC compiler setup. This will be removed in conda-build 4.0. "
	"If this recipe does not use a compiler, this message is safe to ignore. "
	"Otherwise, use {{compiler('<language>')}} jinja2 in requirements/build."
	)

conda-build/conda_build/config.py

Lines 146 to 152 in 9b04330

	# default to not erroring with overlinking for now. We have specified in
	# cli/main_build.py that this default will switch in conda-build 4.0.
	Setting(
	"error_overlinking",
	cc_conda_build.get("error_overlinking", error_overlinking_default).lower()
	== "true",
	),

conda-build/conda_build/cli/main_build.py

Lines 347 to 351 in 9b04330

	help=(
	"Enable error when shared libraries from transitive dependencies are directly "
	"linked to any executables or shared libraries in built packages. This is disabled "
	"by default, but will be enabled by default in conda-build 4.0."
	),

conda-build/docs/source/resources/commands/conda-build.rst

Lines 246 to 256 in 9b04330

	<B>--error-overlinking</B>
	Enable error when shared libraries from transitive dependencies
	are directly linked to any executables or shared libraries in
	built packages. This is disabled by default, but will be enabled
	by default in condabuild 4.0.
	<B>--no-error-overlinking</B>
	Disable error when shared libraries from transitive dependencies
	are directly linked to any executables or shared libraries in
	built packages. This is currently the default behavior, but will
	change in conda-build 4.0.