Fix broken readInt reading through the ring buffer edge

Fixes #363

Author: Sergey Mashkov

core/kotlinx-coroutines-io/src/main/kotlin/kotlinx/coroutines/experimental/io/ByteBufferChannel.kt

@@ -811,8 +811,10 @@ internal class ByteBufferChannel(
     }
 
     private fun ByteBuffer.rollBytes(n: Int) {
+        val rem = remaining()
+
         limit(position() + n)
-        for (i in 1..n - remaining()) {
+        for (i in 0 until n - rem) {
             put(capacity() + ReservedLongIndex + i, get(i))
         }
     }

core/kotlinx-coroutines-io/src/test/kotlin/kotlinx/coroutines/experimental/io/ByteBufferChannelTest.kt

@@ -185,6 +185,41 @@ class ByteBufferChannelTest : TestBase() {
         }
     }
 
+    @Test
+    fun testIntEdge2() {
+        runTest {
+            for (shift in 1..3) {
+                for (i in 1..shift) {
+                    ch.writeByte(1)
+                }
+
+                repeat(Size / 4 - 1) {
+                    ch.writeInt(0xeeeeeeeeL)
+                }
+
+                ch.flush()
+
+                for (i in 1..shift) {
+                    ch.readByte()
+                }
+
+                ch.writeByte(0x12)
+                ch.writeByte(0x34)
+                ch.writeByte(0x56)
+                ch.writeByte(0x78)
+
+                ch.flush()
+
+                while (ch.availableForRead > 4) {
+                    ch.readInt()
+                }
+
+                assertEquals(0x12345678, ch.readInt())
+            }
+        }
+    }
+
+
     @Test
     fun testLongB() {
         runTest {