vppinfra: fix mem map mt issue due to snprintf

vppinfra: fix mem map mt issue due to snprintf

Type: fix

Apparently snprintf is not thread safe!?

Thread 6 "vpp_wk_3" received signal SIGSEGV, Segmentation fault.
[Switching to Thread 0x7ffeed1a3700 (LWP 819375)]
0x00007ffff58fc2b4 in __GI__IO_default_xsputn (n=<optimized out>,
data=<optimized out>, f=<optimized out>) at genops.c:394
394     genops.c: No such file or directory.
(gdb) bt
0  0x00007ffff58fc2b4 in __GI__IO_default_xsputn (n=<optimized out>,
data=<optimized out>, f=<optimized out>) at genops.c:394
1  __GI__IO_default_xsputn (f=0x7ffeec35e050, data=<optimized out>,
n=9) at genops.c:370
2  0x00007ffff58e127c in __vfprintf_internal (s=s@entry=0x7ffeec35e050,
format=format@entry=0x7ffff5f833ce "%s",
    ap=ap@entry=0x7ffeec35e1d0, mode_flags=mode_flags@entry=2) at
../libio/libioP.h:948
3  0x00007ffff58f611a in __vsnprintf_internal (string=0x7ffed57ed018
"", maxlen=<optimized out>, format=0x7ffff5f833ce "%s",
    args=args@entry=0x7ffeec35e1d0, mode_flags=2) at vsnprintf.c:114
4  0x00007ffff5997fd1 in ___snprintf_chk (s=<optimized out>,
maxlen=<optimized out>, flag=<optimized out>, slen=<optimized out>,
    format=<optimized out>) at snprintf_chk.c:38
5  0x00007ffff5f7fd74 in clib_mem_vm_map_internal (base=<optimized
out>, log2_page_sz=<optimized out>, size=<optimized out>,
    fd=<optimized out>, offset=<optimized out>, name=0x0) at
/scratch/fcoras/vpp/src/vppinfra/linux/mem.c:502

Signed-off-by: Florin Coras <fcoras@cisco.com>
Change-Id: I8ff7cfed422273dbdc55068772e11f5e550a9b60