Unbust JVM build with a workaround at the crashsite

Per https://irclog.perlgeek.de/perl6-dev/2017-01-20#i_13961377

src/core/Buf.pm

@@ -12,7 +12,13 @@ my role Blob[::T = uint8] does Positional[T] does Stringy is repr('VMArray') is
     ).throw unless nqp::istype(T,Int);
 
     # other then *8 not supported yet
-    my int $bpe = try { (T.^nativesize / 8).Int } // 1;
+    my int $bpe = try {
+#?if jvm
+        # https://irclog.perlgeek.de/perl6-dev/2017-01-20#i_13961377
+        CATCH { default { Nil } }
+#?endif
+        (T.^nativesize / 8).Int
+    } // 1;
 
     multi method WHICH(Blob:D:) {
         self.^name ~ '|' ~ nqp::sha1(self.decode("latin-1"))