GDB: Fix the mess with value byte/bit range types

GDB: Fix the mess with value byte/bit range types

Consistently use the LONGEST and ULONGEST types for value byte/bit
offsets and lengths respectively, avoiding silent truncation for ranges
exceeding the 32-bit span, which may cause incorrect matching.  Also
report a conversion overflow on byte ranges that cannot be expressed in
terms of bits with these data types, e.g.:

  (gdb) print one_hundred[1LL << 58]
  Integer overflow in data location calculation
  (gdb) print one_hundred[(-1LL << 58) - 1]
  Integer overflow in data location calculation
  (gdb)

Previously such accesses would be let through with unpredictable results
produced.