Remove unused parameter in solib_add and update_solib_list

Remove unused parameter in solib_add and update_solib_list

The target parameter in both solib_add and update_solib_list
functions is not used anymore and as not been used for a while. This
change removes the parameter to clean up the code a little bit.

gdb/ChangeLog:

	* infcmd.c (post_create_inferior): Remove unused argument in
	call to solib_add.
	* remote.c (remote_start_remote): Likewise.
	* solib-frv.c (frv_fetch_objfile_link_map): Likewise.
	* solib-svr4.c: (svr4_fetch_objfile_link_map): Likewise.
	(enable_break): Likewise.
	* solib.c (update_solib_list): Remove unused target argument
	and its documentation.
	(solib_add): Remove unused target argument.  Remove unused
	argument in call to update_solib_list.
	(info_sharedlibrary_command): Remove unused argument in call
	to update_solib_list.
	(sharedlibrary_command): Remove unused argument in call to
	solib_add.
	(handle_solib_event): Likewise.
	(reload_shared_libraries): Likewise.
	* solib.h (solib_add): Remove unused target argument.

Signed-off-by: Marc-Andre Laperle <marc-andre.laperle@ericsson.com>