Reduce scope of i in cfg/info.c:update_info_file()

Found by cppcheck tool.
Use free_chunk() in one more place in engine/keys

Should free it correctly even if used at the moment.

Indirectly suggested by clang static analyzer.
Check return val of to_wide() for NULL in 1 place

Suggested by clang static analyzer.
Always set output arg of read_nonseekable_stream()

Suggested by clang static analyzer.
Initialize [ug]id in chown_cmd() for SCAs

SCA stands for Static Code Analyzer.  Got tired of this false positive.
Fix potential buf overflow on expanding fuse param

Suggested by clang static analyzer.
Handle long destination value for FUSE expansion

Continuing with this function after clang static analyzer suggestion.
Handle long destination value for FUSE expansion

Continuing with this function after clang static analyzer
suggestion.
Fix past-end access in format_mount_command()

Theoretical, but anyway.
Remove useless assignments in undo.c

Found by clang static analyzer.
Remove excess conditional in file_is_visible()

CID 1204134 (#1 of 1): Logically dead code (DEADCODE)

dead_error_line: Execution cannot reach this expression 0 inside
statement sprintf(name_with_slash, "%....
Be more consistent in allocating null list of strs

iCID 1204142 (#1 of 1): Wrong size argument (SIZEOF_MISMATCH)

suspicious_sizeof: Passing argument 1UL to function malloc that
returns a pointer of type char ** is suspicious because a multiple
of sizeof (char *) /*8*/ is expected.
Fix possible memory leaks in vifmrc-converter.c

CID 1204141 (#1 of 1): Resource leak (RESOURCE_LEAK)58. overwrite_var:
Overwriting lwin_dir in lwin_dir = strdup(s1) leaks the storage that
lwin_dir points to.

iCID 1204140 (#1 of 1): Resource leak (RESOURCE_LEAK)86. overwrite_var:
Overwriting rwin_dir in rwin_dir = strdup(s1) leaks the storage that
rwin_dir points to.

CID 1204139 (#1 of 1): Resource leak (RESOURCE_LEAK)121. overwrite_var:
Overwriting color_scheme in color_scheme = strdup(s1) leaks the storage
that color_scheme points to.
Minor code style updates for vifmrc-converter.c
Simplify reading errors of background tasks

No need to create a new buffer to add '\0' at the end.

Indirectly suggested by coverity scan.
A couple of minor style corrections in job_check()

- long line breaking;
- name of a variable from "buf" to "err_msg".
Increase size of bg task error message buffer

Also give it a name to get rid of the magic number.
Skip empty and whitespace only error messages

They are of no use.

This hides such error messages, but is it a real error indication
to output whitespace to stderr?
Fix possible buffer overrun in format_entry_name()

CID 1204143 (#1 of 1): String not null terminated (STRING_NULL)12.
string_null_argument: Function read does not terminate string *buf.
Assert seekable str in get_remaining_stream_size()