readSTLASCII.L: support the change to flex in version 2.5.37

src/triSurface/triSurface/interfaces/STL/readSTLASCII.L

@@ -55,7 +55,7 @@ int yyFlexLexer::yylex()
 // It is called by yylex but is not used as the mechanism to change file.
 // See <<EOF>>
 //! \cond dummy
-#if YY_FLEX_SUBMINOR_VERSION < 34
+#if YY_FLEX_SUBMINOR_VERSION < 34 || YY_FLEX_SUBMINOR_VERSION > 36
 extern "C" int yywrap()
 #else
 int yyFlexLexer::yywrap()