Use std::fill instead of memset

...to avoid GCC 8 -Werror=class-memaccess ("clearing an object of non-trivial
type ‘struct SwSrchChrAttr’").  Similar to
<https://gerrit.libreoffice.org/#/c/48488/> "Allocate ImpXPolygon::pPointAry as
a true Point[]", std::fill appears to produce adequate code here with recent
compilers.

Change-Id: I3ee0bc15e852b80e0429c8e0a4bc48424af9c5a3
Reviewed-on: https://gerrit.libreoffice.org/48518Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Stephan Bergmann <sbergman@redhat.com>

sw/source/core/crsr/findattr.cxx

@@ -43,6 +43,8 @@
 #include <pamtyp.hxx>
 #include <swundo.hxx>
 #include <boost/optional.hpp>
+
+#include <algorithm>
 #include <memory>
 
 using namespace ::com::sun::star;
@@ -183,6 +185,8 @@ struct SwSrchChrAttr
     sal_Int32 nStt;
     sal_Int32 nEnd;
 
+    SwSrchChrAttr(): nWhich(0), nStt(0), nEnd(0) {}
+
     SwSrchChrAttr( const SfxPoolItem& rItem,
                     sal_Int32 nStart, sal_Int32 nAnyEnd )
         : nWhich( rItem.Which() ), nStt( nStart ), nEnd( nAnyEnd )
@@ -253,8 +257,8 @@ SwAttrCheckArr::~SwAttrCheckArr()
 
 void SwAttrCheckArr::SetNewSet( const SwTextNode& rTextNd, const SwPaM& rPam )
 {
-    memset( pFndArr, 0, nArrLen * sizeof(SwSrchChrAttr) );
-    memset( pStackArr, 0, nArrLen * sizeof(SwSrchChrAttr) );
+    std::fill(pFndArr, pFndArr + nArrLen, SwSrchChrAttr());
+    std::fill(pStackArr, pStackArr + nArrLen, SwSrchChrAttr());
     nFound = 0;
     nStackCnt = 0;