[lldb] Note difference in vFile:pread/pwrite format for lldb

https://sourceware.org/gdb/current/onlinedocs/gdb/Host-I_002fO-Packets.html

States that all numbers should be hexidecimal but lldb
uses decimals in vFile:pread and vFile:pwrite.

lldb-server can accept either since it ends up using
strtoull which will detect the base being used.

Reviewed By: labath

Differential Revision: https://reviews.llvm.org/D89227