lscpu: fix shadow declaration [smatch scan]

sys-utils/lscpu.c:572:22: warning: symbol 'fd' shadows an earlier one

Signed-off-by: Sami Kerola <kerolasa@iki.fi>
setarch: prefer preprocessor rather than autotools check

It seems to be pointless to spend time in ./configure phase when
preprocessor has to perform #ifndef check anyway.

Signed-off-by: Sami Kerola <kerolasa@iki.fi>
build-sys: use m4 quoting consistently

Signed-off-by: Sami Kerola <kerolasa@iki.fi>
build-sys: prefer AS_CASE rather than shell 'case'

References: http://www.gnu.org/savannah-checkouts/gnu/autoconf/manual/autoconf-2.69/html_node/Limitations-of-Builtins.html#case
Signed-off-by: Sami Kerola <kerolasa@iki.fi>
build-sys: prefer AS_IF rather than shell 'if'

Signed-off-by: Sami Kerola <kerolasa@iki.fi>
build-sys: use backticks rather than $() for commands in configure

The configure had both backticks and $() in use.  These command
susbstitutions are mutually interchangeable, so one should pick only one
form.  In this case backticks were favored because they are known with
greater range of shells, making the backticks to be more portable.

References: https://www.gnu.org/software/autoconf/manual/autoconf-2.67/html_node/Shell-Substitutions.html#index-g_t_0024_0028_0040var_007bcommands_007d_0029-1632
Signed-off-by: Sami Kerola <kerolasa@iki.fi>
rev: use string printing rather than character output

Fliping a string in memory, and printing it with multibyte output
function makes the command about 1/3 quicker.

Signed-off-by: Sami Kerola <kerolasa@iki.fi>