drawingML export: search for tab only once, not 3 times per line

Change-Id: I4255862d4bfb673dbcf871282f65aa6b1ad4616e

oox/source/export/drawingml.cxx

@@ -1801,8 +1801,10 @@ std::map< OString, std::vector<OString> > lcl_getAdjNames()
     bool bNotDone = aStream.ReadLine(aLine);
     while (bNotDone)
     {
-        OString aKey = aLine.getToken(0, '\t');
-        OString aValue = aLine.getToken(1, '\t');
+        sal_Int32 nIndex = 0;
+        // Each line is in a "key\tvalue" format: read the key, the rest is the value.
+        OString aKey = aLine.getToken(0, '\t', nIndex);
+        OString aValue = aLine.copy(nIndex);
         aRet[aKey].push_back(aValue);
         bNotDone = aStream.ReadLine(aLine);
     }