Fix compiler warning (-Wmaybe-uninitialized)

gcc warning:

    src/lstm/recodebeam.cpp:270:41: warning: ‘current_char’ may be used uninitialized in this function [-Wmaybe-uninitialized]

It's a false positive, but setting the variable to 0 satisfies the compiler.

Signed-off-by: Stefan Weil <sw@weilnetz.de>

src/lstm/recodebeam.cpp

@@ -197,7 +197,7 @@ void RecodeBeamSearch::ExtractBestPathAsWords(const TBOX& line_box,
     DebugUnicharPath(unicharset, second_nodes, unichar_ids, certs, ratings,
                      xcoords);
   }
-  int current_char;
+  int current_char = 0;
   int timestepEnd = 0;
   //if lstm choice mode is required in granularity level 2 it stores the x
   //Coordinates of every chosen character to match the alternative choices to it