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.

just in case one would use the function directly. The use of
ZEND_SECURE_ZERO could be eliminated now, too. Or it can be
kept for BC.

checking presence of the function if older versions of NetBSD

Signed-off-by: Gabriel Caruso <carusogabriel34@gmail.com>

Using the weak symbol explicit_bzero_hook does not work if LTO is
enabled. Instead avoid memset optimizations using an asm memory
barrier.

Use a fallback implementation where the memory is zeroed through
volatile.

since 1999 algorithms have changed and register k/w
not necessary anymore.