The POSIX standard says, that `fcntl.h` is to be included as `#include <fcntl.h>`.
This change fixes the compiler warnings that happen with `musl` libc :
```
/usr/include/sys/fcntl.h:1:2: warning: #warning redirecting incorrect #include <sys/fcntl.h> to <fcntl.h> [-Wcpp]
1 | #warning redirecting incorrect #include <sys/fcntl.h> to <fcntl.h>
| ^~~~~~~
In file included from /home/ferenc/github.com/organicmaps/organicmaps/libs/coding/mmap_reader.cpp:18,
from /home/ferenc/github.com/organicmaps/organicmaps/build-alpine-3.21/build-alpine-3.21/libs/coding/CMakeFiles/coding.dir/Unity/unity_0_cxx.cxx:40:
/usr/include/sys/fcntl.h:1:2: warning: #warning redirecting incorrect #include <sys/fcntl.h> to <fcntl.h> [-Wcpp]
1 | #warning redirecting incorrect #include <sys/fcntl.h> to <fcntl.h>
| ^~~~~~~
````
This happens because of the explicit [warning in the proxy header](
https://git.musl-libc.org/cgit/musl/tree/include/sys/fcntl.h)
Signed-off-by: Ferenc Géczi <ferenc.gm@gmail.com>
