Remove code from inflate.c and infback.c that is impossible to execute.

During coverage testing it was discovered that these two lines could
never pull more bits, since the immediately preceding for loop assures
that all of the code's bits are already pulled.

infback.c

@@ -403,7 +403,6 @@ void FAR *out_desc;
                     PULLBYTE();
                 }
                 if (here.val < 16) {
-                    NEEDBITS(here.bits);
                     DROPBITS(here.bits);
                     state->lens[state->have++] = here.val;
                 }

inflate.c

@@ -944,7 +944,6 @@ int flush;
                     PULLBYTE();
                 }
                 if (here.val < 16) {
-                    NEEDBITS(here.bits);
                     DROPBITS(here.bits);
                     state->lens[state->have++] = here.val;
                 }