Bug 18780: Translatability: Get rid of exposed tt directive in masthead-langmenu.inc

The file opac-tmpl/bootstrap/en/includes/masthead-langmenu.inc exposes following tt directive to translators:

"[%% IF ( ( opaclanguagesdisplay ) && ( ! one_language_enabled ) && "
"( languages_loop ) && ( OpacLangSelectorMode == 'both' || "
"OpacLangSelectorMode == 'top') ) %%] "

This patch fixes it.

To test:
- Apply patch
- Verify that language selector in OPAC (top of the page) works as expected
- Bonus test: create a new language 'aa-AA', verify that line above does not
show up in aa-AA-opac-bootstrap.po

NOTE: Followed a test plan similar to bug 18776 comment 3

Signed-off-by: Mark Tompsett <mtompset@hotmail.com>

Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
(cherry picked from commit 255cadeb77)
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>

koha-tmpl/opac-tmpl/bootstrap/en/includes/masthead-langmenu.inc

@@ -1,9 +1,5 @@
-
-[% IF ( ( opaclanguagesdisplay )   &&
-        ( ! one_language_enabled ) &&
-        ( languages_loop )         &&
-        ( OpacLangSelectorMode == 'both' || OpacLangSelectorMode == 'top') )
-%]
+[%# Following on one line for translatability %]
+[% IF ( ( opaclanguagesdisplay ) && ( ! one_language_enabled ) && ( languages_loop ) && ( OpacLangSelectorMode == 'both' || OpacLangSelectorMode == 'top') ) %]
 <li class="dropdown">
   <a href="#" title="Switch languages" class="dropdown-toggle" id="langmenu" data-toggle="dropdown" role="button"><i class="icon-flag icon-white"></i> <span class="langlabel">Languages</span> <b class="caret"></b></a>
     <ul aria-labelledby="langmenu" role="menu" class="dropdown-menu">