CLEANUP: stats: Avoid computation with uninitialized bits.

stats_map_lookup() sets bit SMP_F_CONST in the uninitialized member
flags of a stack-allocated sample, leaving the other bits
uninitialized.  All code paths that can access the struct only ever
check for this specific flag, so there is no risk of unintended
behavior.

Nevertheless fix it as it triggers warnings in static code analysis
tools and might become a problem on future revisions of the code.

Problem found in version 1.5.
(cherry picked from commit 9727cf482cc4f761a2649fd04149f17bb3143600)
(cherry picked from commit a1a1565766d5f74dac4c7f3fda227dedd01259cd)
1 file changed