[doc PATCH] Fix backward compatibility in target feature specs

[Doug Evans <dje at google dot com>]

Hi.

This is a follow-on to these two patches:

https://sourceware.org/ml/gdb-patches/2016-08/msg00105.html
https://sourceware.org/ml/gdb-patches/2016-08/msg00106.html

to update the documentation.

2016-08-08  Doug Evans  <dje@google.com>

	* gdb.texinfo (Target Description Format): Update docs on "end"
	field spec and field default type.

diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
index f5dde61..0b5ec39 100644
--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -40681,16 +40681,13 @@ Bitfield values may be named with the empty  
string, @samp{""},
 in which case the field is ``filler'' and its value is not printed.
 Not all bits need to be specified, so ``filler'' fields are optional.

-The @var{start} value is required, and @var{end} and @var{type}
-are optional.
+The @var{start} and @var{end} values are required, and @var{type}
+is optional.
 The field's @var{start} must be less than or equal to its @var{end},
 and zero represents the least significant bit.
-The default value of @var{end} is @var{start}, a single bit field.

-The default value of @var{type} depends on whether the
-@var{end} was specified.  If @var{end} is specified then the default
-value of @var{type} is an unsigned integer.  If @var{end} is unspecified
-then the default value of @var{type} is @code{bool}.
+The default value of @var{type} is @code{bool} for single bit fields,
+and an unsigned integer otherwise.

 Which to choose?  Structures or flags?