react-bootstrap: Add bsClass to Glyphicon

See https://react-bootstrap.github.io/components.html#glyphicons-props

types/react-bootstrap/lib/Glyphicon.d.ts

@@ -4,6 +4,8 @@ declare namespace Glyphicon {
     export interface GlyphiconProps extends React.HTMLProps<Glyphicon> {
         // Required
         glyph: string;
+        // Optional
+        bsClass?: string;
     }
 }
 declare class Glyphicon extends React.Component<Glyphicon.GlyphiconProps> { }