Always use unsigned char

char is unsigned by default on ARM, so make it so on other architectures as well

Bug: 37208566
Test: ran poc with and without change, ran CTS on x86 and ARM
Change-Id: I264db1dad884de7fd8f932cd9571199a1c517f6a
(cherry picked from commit 220e1a7b6c3fec4cee6af028c9e7de9c4cc6aabc)
1 file changed