[PDB] Handle char as a builtin type
Summary:
`char`, `signed char` and `unsigned char` are three different types,
and they are mangled differently:
```
void __declspec(dllexport) /* ?foo@@YAXD@Z */ foo(char c) { }
void __declspec(dllexport) /* ?foo@@YAXE@Z */ foo(unsigned char c) { }
void __declspec(dllexport) /* ?foo@@YAXC@Z */ foo(signed char c) { }
```
This commit separates `char` from `signed char` and `unsigned char`.
Reviewers: asmith, zturner, labath
Reviewed By: asmith, zturner
Subscribers: teemperor, lldb-commits, stella.stamenova
Tags: #lldb
Differential Revision: https://reviews.llvm.org/D52468
llvm-svn: 343298
ec97b523be