CLASSICAL Martinu, Bohuslav: Concerto No. 5 in B-flat for Piano and Orchestra, H. 366 (''Fantasia Concertante''). Ales Bilek, piano. Prague Symphony Orchestra, Jindrich Rohan, conductor. Concerto for Two Pianos, H. 292. Vera Lejskova & Vlastimil Lejsek, pianos. Brno State Philharmonic Orchestra, Jiri Waldhans, conductor. (Pro Arte Pal-1034.) - Many composers have had major revivals these past few decades. It is now time that Martinu got his fair hearing. His music has beauty, passion, and individuality, as these two works clearly prove. The Fifth Piano Concerto, in particular, is vintage Martinu, and anyone wanting to know what that involves need search no further. The two-piano concerto is more long-winded: It is an earlier work, and he was still honing his craft, working on the sound that would instantly identify his music. This is a most welcome record. The performances are forceful, earnest, communicative.