Adjust the encoding and format applied to i387_ext and vec* type
registers from gdbserver to match lldb-server. Both types are now
displayed as vector of uint8 instead of float and integer formats used
before. Additionally, this fixes display of STi registers when they do
not carry floating-point data (they are also used to hold MMX vectors).
Differential Revision: https://reviews.llvm.org/D108468
bda5fe8f0c