compare-sections: New -r option.

When connecting to a remote system, we use the compare-sections
command to verify that the box is running the code that we think it is
running.  Since the system is up and running and *NOT* 'freshly
downloaded without yet executing anything', read-write sections, of
course, differ from what they were in the executable file.

Comparing read-write sections takes time and more importantly the
MIS-MATCHED output is confusing to some users.

The compare-sections command compares all loadable sections including
read-write sections.  This patch gives the user the option to compare
just the loadable read-only sections.

gdb/
2014-05-01  David Taylor  <dtaylor@emc.com>

	* remote.c (compare_sections_command): Add -r option to compare
	all loadable read-only sections.

gdb/doc/
2014-05-01  David Taylor  <dtaylor@emc.com>

	* gdb.texinfo (compare-sections): Document the new -r (read-only)
	option.