Revert r330897:

This was intended to be a non-functional change. It wasn't. The commit
message was thus wrong. In addition it broke arm, and merged crypto
related code.

Revert with prejudice.

This revert skips files touched in r316370 since that commit was since
MFCed. This revert also skips files that require $FreeBSD$ property
changes.

Thank you to those who helped me get out of this mess including but not
limited to gonzo, kevans, rgrimes.

Requested by: gjb (re)

Partial merge of the SPDX changes

These changes are incomplete but are making it difficult
to determine what other changes can/should be merged.

No objections from: pfg

Copy head@r302406 to stable/11 as part of the 11.0-RELEASE cycle.
Prune svn:mergeinfo from the new branch, as nothing has been merged
here.

Additional commits post-branch will follow.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

In reallocf(3), free the memory only when size != 0. Otherwise, when the
System V compatibility option (malloc "V" flag) is in effect a zero sized
reallocf() could cause a double free.

PR: bin/141753
Submitted by: Dan Lukes

Fix the style of the SCM ID's.
I believe have made all of libc .c's as consistent as possible.

$Id$ -> $FreeBSD$

Fix style problems noted by Bruce:
o No copyright on reallocf.
o Order makefile list correctly.
o indent reallocf properly.

Add reallocf to the library. This function is simliar to realloc, but
when it returns NULL to indicate failure, it will also free the memory
that was passed to it, if that was non-null.

This does not change the semantics of realloc.

A second commit will be done to commit the conversion of those places in
the code that can safely use this to avoid memory leaks when confronted
with low memory situations.

Beaten-to-death-but-finally-approved-in: -current