Search for libtiff library file first on Windows and macOS

[radarhere]

libtiff takes priority over tiff on Windows and macOS

Pillow/setup.py

Lines 757 to 762 in 2954964

	if _find_library_file(self, "tiff"):
	feature.set("tiff", "tiff")
	if sys.platform in ["win32", "darwin"] and _find_library_file(
	self, "libtiff"
	):
	feature.set("tiff", "libtiff")

This rearranges the code so that if it is found, we skip searching for tiff.