Ignore missing font in fontchain_linter.py

It is totally valid if the font is missing even if the font is listed in
fonts.xml. Android Watch has less fonts and OEM vendor may reduce the
font files.

Bug: 72159040
Test: m fontchain_lint
Change-Id: I22bdf7bfeb6d80a2a338ebf7536c8eaf193b03c5
1 file changed