CID#18499 Resource leak

Error handling could lead to a resource leak of
the struct pointed by task if allocation of mul
failed. The fix is a bit longer than the previous
version but it's more readable and avoids a
resource leak.
CID#18466 Missing break in switch

Missing break for LAYOUTRETURN4_FSID case leading
to a fallthrough to the next case.
CID#18465 Missing break in switch

Missing break for case 123 leads to a
fallthrough to the default case used
for error handling.
CID#18453 Explicit null dereferenced

son_owner_val struct member of oname wasn't
initialized before calling memcpy. Thus, leading
to a segfault.
Moreover, this section of the code is only used
if 9P support was activated at build time. oname
isn't used at all in the general case.
CID#18447 Logically dead code

Whatever the course of action, found is set
to TRUE (1) anyway. The last conditionnal
statement isn't needed. This makes the code
a little more simple.
CID#18444 Copy-paste error

Simple typo here, should be mtime instead
of atime.