Make init_msg a uint8_t*.

It's current a void* and gets explicitly cast everywhere. Make it a uint8_t and
only add the casts when converting it come init_buf, which internally stores a
char*.

Change-Id: I28bed129e46ed37ee1ce378d5c3bd0738fc1177f
Reviewed-on: https://boringssl-review.googlesource.com/1163
Reviewed-by: Adam Langley <agl@google.com>
6 files changed