Fix char limits
Fix char limits

By the standard CHAR_MIN and CHAR_MAX should be 0 and UCHAR_MAX respectively when char implementation is unsigned ( -fno-signed-char)

mirror/tinycc,mingodad/tinycc,mirror/tinycc,mingodad/tinycc,mingodad/tinycc,mirror/tinycc,mingodad/tinycc,mirror/tinycc