base64: simplify end handling in av_base64_encode()

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavutil/base64.c

@@ -99,14 +99,11 @@ char *av_base64_encode(char *out, int out_size, const uint8_t *in, int in_size)
         i_bits = (i_bits << 8) + *in++;
         bytes_remaining--;
         i_shift += 8;
-
-        do {
+    }
+    while (i_shift > 0) {
         *dst++ = b64[(i_bits << 6 >> i_shift) & 0x3f];
         i_shift -= 6;
-        } while (i_shift > 6);
     }
-    if (i_shift > 0)
-        *dst++ = b64[(i_bits << 6 >> i_shift) & 0x3f];
     while ((dst - ret) & 3)
         *dst++ = '=';
     *dst = '\0';