Make -Wformat accept printf("%hhx", c); with -funsigned-char

For "%hhx", printf expects an unsigned char. This makes Clang
accept a 'char' argument for that also when using -funsigned-char.

This fixes PR12761.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@156388 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed