Correctly initialize the TUI locator window

Correctly initialize the TUI locator window

The call to tui_alloc_content in tui_set_locator_info passes
locator->type as the type of the window whose content is being
allocated.  This may seem correct but it's actually not because when
this code path actually get executed locator->type has not yet been to
set LOCATOR_WIN so it defaults to 0 i.e. SRC_WIN.  Thus we allocate the
content of the locator window as if it was the source window.  This
oversight turns out not to be a big deal in practice but the patch that
follows depends on the locator's proc_name and full_name arrays to be
initialized to the empty string which is done by tui_alloc_content if
we pass to it LOCATOR_WIN.

This patch fixes this bug by explicitly passing LOCATOR_WIN to
tui_alloc_content.

gdb/ChangeLog:

	* tui/tui-stack.c (tui_set_locator_info): Explicitly pass
	LOCATOR_WIN to tui_alloc_content.