meson: switch getpeer* checks to autotools style

Checking for function "getpeereid" : YES
Checking for function "getpeerucred" : NO
[...]
include/meson.build:182:7: ERROR: Argument to "not" is not a boolean.

Fixes: 68c2cfad ("meson: Make sure defines are either set to 1 or not defined")
4 jobs for freebsd-meson-xwayland in 4 minutes and 11 seconds
Status Job ID Name Coverage
  Docker Image
passed debian-buster #8715885

00:00:29

 
  Build And Test
passed autotools #8715886

00:03:41

passed meson #8715887

00:01:53

passed meson-noglamor #8715888

00:01:45