ubifs-utils: ubifs.h: Include <fcntl.h>

ubifs-utils: ubifs.h: Include <fcntl.h>

Include the <fcntl.h> header file to fix the following error
when building with musl:

| In file included from ../git/ubifs-utils/common/compr.c:42:
| ../git/ubifs-utils/libubifs/ubifs.h:313:9: error: unknown type name 'loff_t'; did you mean 'off_t'?
|   313 |         loff_t ui_size;
|       |         ^~~~~~
|       |         off_t
| ../git/ubifs-utils/libubifs/ubifs.h:1341:9: error: unknown type name 'loff_t'; did you mean 'off_t'?
|  1341 |         loff_t i_size;
|       |         ^~~~~~
|       |         off_t
| ../git/ubifs-utils/libubifs/ubifs.h:1342:9: error: unknown type name 'loff_t'; did you mean 'off_t'?
|  1342 |         loff_t d_size;
|       |         ^~~~~~
|       |         off_t
| ../git/ubifs-utils/libubifs/ubifs.h:1899:44: error: unknown type name 'loff_t'; did you mean 'off_t'?
|  1899 |                              int deletion, loff_t new_size);
|       |                                            ^~~~~~
|       |                                            off_t
| make: *** [Makefile:4878: ubifs-utils/common/mkfs_ubifs-compr.o] Error 1

Signed-off-by: Fabio Estevam <festevam@gmail.com>
Reviewed-by: Zhihao Cheng <chengzhihao1@huawei.com>
Reviewed-by: Khem Raj <raj.khem@gmail.com>
Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>