Split glibc version detection in two #if directives.

If __GLIBC_PREREQ is undefined, the single-line version expands to
'#if 0 && 0(2,4)', which causes a syntax error.

PR: 54275


git-svn-id: https://svn.apache.org/repos/asf/apr/apr/trunk@1422413 13f79535-47bb-0310-9956-ffa450edef68
doc fixes


git-svn-id: https://svn.apache.org/repos/asf/apr/apr/trunk@1425356 13f79535-47bb-0310-9956-ffa450edef68
Fixup r1422413 so that memset is used on non-glibc platforms

Noticed by Alan Hourihane <alanh fairlite co uk>


git-svn-id: https://svn.apache.org/repos/asf/apr/apr/trunk@1426442 13f79535-47bb-0310-9956-ffa450edef68
Fix docs for apr_queue_trypop

PR: 54328
Submitted by: Javier Alcázar <javucho1000 yahoo com mx>


git-svn-id: https://svn.apache.org/repos/asf/apr/apr/trunk@1426448 13f79535-47bb-0310-9956-ffa450edef68