accept blanks after ">>" in check_source_format_directive

gcc/cobol/lexio.cc

@@ -340,7 +340,7 @@ check_source_format_directive( filespan_t& mfile ) {
   if( ! (p < mfile.eol && p[1] == *p ) ) return;
 
   const char pattern[] =
-    ">>source[[:blank:]]+"
+    ">>[[:blank:]]*source[[:blank:]]+"
     "(format[[:blank:]]+)?"
     "(is[[:blank:]]+)?"
     "(fixed|free)";