Open /dev/mhvtlXX node in exclusive mode

It doesn't make sense to allow multi-access to the device node anyway.

Signed-off-by: Mark Harvey <markh794@gmail.com>
vtllibrary: Fix storage leak on re-initiaization

rereadconfig() did not free all malloc() mem correctly
resulting in memory leak of mode/log page info each time

Leak identified by valgrind.
==8915== Invalid read of size 4
==8915==    at 0x40663D: rereadconfig (vtllibrary.c:1329)
==8915==    by 0x403E80: processMessageQ (vtllibrary.c:621)
==8915==    by 0x407D9B: main (vtllibrary.c:1697)
==8915==  Address 0x4e483e0 is 16 bytes inside a block of size 48 free'd
==8915==    at 0x4A063F0: free (vg_replace_malloc.c:446)
==8915==    by 0x40655B: rereadconfig (vtllibrary.c:1323)
==8915==    by 0x403E80: processMessageQ (vtllibrary.c:621)
==8915==    by 0x407D9B: main (vtllibrary.c:1697)

Signed-off-by: Mark Harvey <markh794@gmail.com>