* dwarf2expr.h: Tweak comment.

(struct dwarf_expr_context): Use `gdb_byte *' in read_mem and
get_frame_base function pointers.
(read_uleb128, read_sleb128): Change return type and types of
first two arguments to `gdb_byte *'.
(dwarf2_read_address): Change types of first two arguments to
`gdb_byte *'.
* dwarf2expr.c: Tweak comment.
(dwarf_expr_eval): Change type of second argument to `gdb_byte *'.
(read_uleb128, read_sleb128): Change return type and types of
first two arguments to `gdb_byte *'.
(dwarf2_read_address): Change types of first two arguments to
`gdb_byte *'.
(execute_stack_op): Change types of last two arguments to
`gdb_byte *'.  Use `gdb_byte *' for byte buffers.
* dwarf2loc.h: Tweak comment.
(struct dwarf2_locexpr_baton, struct dwarf2_loclist_baton): Use
`gdb_byte *' for byte buffers.
* dwarf2loc.c (find_location_expression): Change return type to
`gdb_byte *'.  Use `gdb_byte *' for byte buffers.  Change length
to `unsigned int'.
(dwarf_expr_read_reg): Use `gdb_byte *' for byte buffer.  Remove
bogus cast.
(dwarf_expr_read_mem): Change type of second argument to
`gdb_byte *'.
(dwarf_expr_frame_base): Change type of second argument to
`gdb_byte **'.
(dwarf2_evaluate_loc_desc): Change type of third argument to
`gdb_byte *'.
(needs_frame_read_mem): Change type of second argument to
`gdb_byte *'.
(needs_frame_frame_base): Change type of second argument
`gdb_byte **'.  Use gdb_byte for lit0.
(dwarf2_tracepoint_var_ref): Change type of fourth argument to
`gdb_byte *'.  Use `gdb_byte *' for byte buffer.
(loclist_read_variable, loclist_tracepoint_var_ref): Use `gdb_byte
*' for byte buffer.
* dwarf2-frame.c (struct dwarf2_cie, struct dwarf2_fde)
(struct dwarf2_frame_state): Use gdb_byte instead of `unsigned
char'.
(read_reg): Use `gdb_byte *' for byte buffers.  Remove redundant
cast.
(read_mem): Change second argument to `gdb_byte *'.
(no_get_frame_base): Change second argument to `gdb_byte **'.
(execute_stack_op): Change first argument to `gdb_byte *'.
(execute_cfa_program): Change first two arguments to `gdb_byte *'.
Use gdb_byte instead of `unsigned int'.  Use temprorary variable
to store result of read_uleb128.
(struct comp_unit): Use `gdb_byte *' for byte buffers.
(read_1_byte, read_4_bytes, read_8_bytes): Change last argument to
`gdb_byte *'.
(read_unsigned_leb128, read_signed_leb128): Change second argument
to `gdb_byte *'.  Use gdb_byte instead of `unsigned char'.
(read_initial_length): Change second argument to `gdb_byte *'.
Remove redundant casts.
(read_encoded_value): Use gdb_byte instead of `unsigned char'.
Remove bogus casts.
(decode_frame_entry_1): Change return type and second argument to
`gdb_byte *'.  Use `gdb_byte *' for byte buffers.  Use gdb_byte
instead of `unsigned char'.
(decode_frame_entry): Change return type and second argument to
`gdb_byte *'.  Use `gdb_byte *' for byte buffers.
(dwarf2_build_frame_info): Use `gdb_byte *' for byte buffers.