Fix syntax highlighting for def-style Python functions, with their
parameters spanning multiple lines. E.g. the following should match as
valid Python code in Bitbake recipes:
def myFunction(one, two, \
three, four):
pass
For this to work, use the prefix modifier "\_" before the wildcard ".",
to also match newline characters.
closes: vim/vim#185655fe4faa711
Co-authored-by: Martin Schwan <m.schwan@phytec.de>