Take into account the more correct behavior of recent Linux kernels.

diff --git a/dlls/kernel/tests/pipe.c b/dlls/kernel/tests/pipe.c
index 97931ca..8119164 100644
--- a/dlls/kernel/tests/pipe.c
+++ b/dlls/kernel/tests/pipe.c
@@ -151,9 +151,8 @@
         }
         else
             ok(readden == sizeof(obuf), "peek3 got %ld bytes\n", readden);
-        todo_wine {
+        if (avail != sizeof(obuf)) /* older Linux kernels only return the first write here */
             ok(avail == sizeof(obuf) + sizeof(obuf2), "peek3 got %ld bytes available\n", avail);
-        }
         pbuf = ibuf;
         ok(memcmp(obuf, pbuf, sizeof(obuf)) == 0, "pipe content 3a check\n");
         if (pipemode == PIPE_TYPE_BYTE) {
@@ -184,9 +183,8 @@
         }
         else
             ok(readden == sizeof(obuf), "peek4 got %ld bytes\n", readden);
-        todo_wine {
+        if (avail != sizeof(obuf)) /* older Linux kernels only return the first write here */
             ok(avail == sizeof(obuf) + sizeof(obuf2), "peek4 got %ld bytes available\n", avail);
-        }
         pbuf = ibuf;
         ok(memcmp(obuf, pbuf, sizeof(obuf)) == 0, "pipe content 4a check\n");
         if (pipemode == PIPE_TYPE_BYTE) {
@@ -230,9 +228,8 @@
             ok(written == sizeof(obuf2), "write file len 3b\n");
             ok(PeekNamedPipe(hFile, ibuf, sizeof(ibuf), &readden, &avail, NULL), "Peek5\n");
             ok(readden == sizeof(obuf), "peek5 got %ld bytes\n", readden);
-            todo_wine {
+            if (avail != sizeof(obuf)) /* older Linux kernels only return the first write here */
                 ok(avail == sizeof(obuf) + sizeof(obuf2), "peek5 got %ld bytes available\n", avail);
-            }
             pbuf = ibuf;
             ok(memcmp(obuf, pbuf, sizeof(obuf)) == 0, "content 5a check\n");
             ok(ReadFile(hFile, ibuf, sizeof(ibuf), &readden, NULL), "ReadFile\n");
@@ -262,9 +259,8 @@
             ok(written == sizeof(obuf2), "write file len 6b\n");
             ok(PeekNamedPipe(hnp, ibuf, sizeof(ibuf), &readden, &avail, NULL), "Peek6\n");
             ok(readden == sizeof(obuf), "peek6 got %ld bytes\n", readden);
-            todo_wine {
+            if (avail != sizeof(obuf)) /* older Linux kernels only return the first write here */
                 ok(avail == sizeof(obuf) + sizeof(obuf2), "peek6b got %ld bytes available\n", avail);
-            }
             pbuf = ibuf;
             ok(memcmp(obuf, pbuf, sizeof(obuf)) == 0, "content 6a check\n");
             ok(ReadFile(hnp, ibuf, sizeof(ibuf), &readden, NULL), "ReadFile\n");