There have been multiple reports of large slowdowns due to the
use of MADV_HUGEPAGE, so make it conditional on
USE_ZEND_ALLOC_HUGE_PAGES, just like MAP_HUGETLB already is.

Reapply changes for Zend fixed mapping but only for FreeBSD.
Other BSD might expose some day a similar flag (private
for OpenBSD for the moment for example).
The Linux's part could be brought back but not before 7.4,
at this time, distributions with kernel > 4.17 will be
more widely available.

This reverts commit 0f68ff5c92924deb9401ce66458e67f250ccde74.

This reverts commit 446b5b15d324dacd30f58313563a9d625fb54ac8.

When using mmap with MAP_FIXED_NOREPLACE or MAP_FIXED|MAP_EXCL
an mmap failure is not an error condition, so do not print an
error message in this case.

We did not use MAP_FIXED here, because it may replace an existing
mapping. This commit adds support for MAP_FIXED_NOREPLACE (available
on newer Linux kernels) and MAP_FIXED|MAP_EXCL (available on FreeBSD),
which avoid this issue.

The $Id$ keywords were used in Subversion where they can be substituted
with filename, last revision number change, last changed date, and last
user who changed it.

In Git this functionality is different and can be done with Git attribute
ident. These need to be defined manually for each file in the
.gitattributes file and are afterwards replaced with 40-character
hexadecimal blob object name which is based only on the particular file
contents.

This patch simplifies handling of $Id$ keywords by removing them since
they are not used anymore.