[ticket/10945] remove trigger_error call

removes trigger_error call incase no search results are found or start
variable exceeds the amount. So that search query is displayed in the
search box even if no results are returned.

PHPBB3-10945
[ticket/10945] Display search query when search fails in native search

If search fails and common words are present, split_keywords returns false
and search.php file prints appropriate message of common words.
If search fails and there are no common words, split_keywords returns true
and keyword_search returns false so that the search query is displayed in
search box.

PHPBB3-10945
[ticket/10945] Fix return values for split_keywords function

The function now returns false if all the words are common words and true
otherwise.

PHPBB3-10945
Merge branch 'ticket/10945' into ticket/10945-develop

* ticket/10945:
  [ticket/10945] Fix return values for split_keywords function
  [ticket/10945] Display search query when search fails in native search
  [ticket/10945] remove trigger_error call

Conflicts:
	phpBB/phpbb/search/fulltext_native.php
[ticket/10945] Remove mark test incomplete for mysql and postgres

PHPBB3-10945
[ticket/10945] Fix Unit Tests as per new changes to split_keywords

PHPBB3-10945
[ticket/10945] Remove mark test incomplete for native search backend

PHPBB3-10945
Merge remote-tracking branch 'remotes/dhruvgoel92/ticket/10945' into develop-olympus

* remotes/dhruvgoel92/ticket/10945:
  [ticket/10945] Fix return values for split_keywords function
  [ticket/10945] Display search query when search fails in native search
  [ticket/10945] remove trigger_error call
Merge remote-tracking branch 'remotes/dhruvgoel92/ticket/10945-develop' into develop

* remotes/dhruvgoel92/ticket/10945-develop:
  [ticket/10945] Remove mark test incomplete for native search backend
  [ticket/10945] Fix Unit Tests as per new changes to split_keywords
  [ticket/10945] Remove mark test incomplete for mysql and postgres
  [ticket/10945] Fix return values for split_keywords function
  [ticket/10945] Display search query when search fails in native search
  [ticket/10945] remove trigger_error call
Merge branch 'develop-olympus' into develop

* develop-olympus: