Summary:
Both EOF and the max value of unsigned char is platform dependent. In this
patch we try our best to deduce the value of EOF from the Preprocessor,
if we can't we fall back to -1.
Reviewers: Szelethus, NoQ
Subscribers: whisperity, xazax.hun, kristof.beyls, baloghadamsoftware, szepet, rnkovacs, a.sidorin, mikhail.ramalh
Tags: #clang
Differential Revision: https://reviews.llvm.org/D74473