[clang-scan-deps] Dependency directives source minimizer:

[clang-scan-deps] Dependency directives source minimizer:
single quotes are not digit separators after a valid character literal prefix

The single quote character can act as a c++ digit separator.
However, the minimizer shouldn't treat it as such when it's actually following
a valid character literal prefix, like L, U, u, or u8.

Differential Revision: https://reviews.llvm.org/D64525

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@365700 91177308-0d34-0410-b5e6-96231b3b80d8