Indent multiline call-seq comment

[tompng]

Multiline call-seq should be indented.
Unindented call-seq is ambiguous. There is a pull request ruby/rdoc#1149 that changes unindented call-seq parsing result.

/*
 * call-seq:
 * Foo(int) -> Bar
 *
 * Foo is a method. This line looks like a document but part of call-seq
 *
 * Document starts from this line
 */

Spaces before /* will be deleted before call-seq extracting phase. Indent calculation does not work well.

      /* call-seq:
       * callseq(int)
       * 
       * comment
       */

comment =
"/* call-seq:
       * callseq(int)
       * 
       * comment
       */"

-      /* call-seq:
+      /*
+       * call-seq: