LU-14093 lutf: fix build with gcc10

LU-14093 lutf: fix build with gcc10

The new LUTF code has build issues with gcc10. I see the following
build errors.

ld: lutf-lutf_listener.o:lutf.h:88: multiple definition of `g_lutf_cfg'
ld: lutf-lutf_listener.o:lutf.h:22: multiple definition of `debugtimestr'
ld: lutf-lutf_listener.o:lutf.h:21: multiple definition of `di'
ld: lutf-lutf_listener.o:lutf.h:20: multiple definition of `debugnow'

In function ‘snprintf’,
    inlined from ‘python_run_interactive_shell’ at lutf_python.c:45:2:
stdio2.h:71:10: error: ‘%s’ directive argument is null [-Werror=format-truncation=]
   71 |   return __builtin___snprintf_chk (__s, __n, __USE_FORTIFY_LEVEL - 1,
      |          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   72 |        __glibc_objsize (__s), __fmt,
      |        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   73 |        __va_arg_pack ());
      |        ~~~~~~~~~~~~~~~~~

This patch resolves these warnings. Without this patch LUTF will
not build on Ubuntu 20 LTS.

Test-Parameters: trivial
Change-Id: Ie3c99f8c6cf2f5de583dc95a0dc63fcde1aa6ffd
Signed-off-by: James Simmons <jsimmons@infradead.org>
Reviewed-on: https://review.whamcloud.com/44484
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Serguei Smirnov <ssmirnov@whamcloud.com>
Reviewed-by: Alex Zhuravlev <bzzz@whamcloud.com>
Reviewed-by: Amir Shehata <ashehata@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>