Updates to example application cells

They're renamed because their types differ from those in `stdio.h`.  As part of that change I commented out the inclusion of that header in attempt to resolve this:
```
[apps/cell1] building...
make[2]: Entering directory `/home/cygnus/sk/dev-seL4/build/seL4/build/arm/imx6/cell1'
 [HEADERS]
 [STAGE] autoconf.h
 [CC] src/main.o
In file included from /home/cygnus/sk/dev-seL4/build/seL4/stage/arm/imx6/include/stdio.h:21:0,
                 from /home/cygnus/sk/dev-seL4/build/seL4/apps/cell1/src/main.c:14:
/home/cygnus/sk/dev-seL4/build/seL4/stage/arm/imx6/include/bits/alltypes.h:4:18: error: conflicting types for 'size_t'
In file included from /home/cygnus/sk/dev-seL4/build/seL4/stage/arm/imx6/include/cell1/cell1_driver.h:4:0,
                 from /home/cygnus/sk/dev-seL4/build/seL4/apps/cell1/src/main.c:12:
/home/cygnus/sk/dev-seL4/build/seL4/stage/arm/imx6/include-libskc/stddef.h:15:23: note: previous declaration of 'size_t' was here
make[2]: *** [src/main.o] Error 1
make[2]: Leaving directory `/home/cygnus/sk/dev-seL4/build/seL4/build/arm/imx6/cell1'
make[1]: *** [cell1] Error 2
make[1]: Leaving directory `/home/cygnus/sk/dev-seL4/build/seL4'
make: *** [seL4] Error 2
```
My thinking on this change was that libmuslc's output routines were going to the wrong serial device in one of the cells, and I never wanted that, even in debug builds, so I wrote the cells to use output routines that only emitted to the right device.  I also don't recall doing debug builds so I never tested that code path.  I'll clean these changes up in light of your comments and see if I can't line them up more with how things were before.