Create crtsavres.o for powerpc builds

[jhibbits]

Summary

GCC expects to link in a crtsavres.o on powerpc platforms. On
powerpc64 this is an empty file, but on powerpc and powerpcspe this does contain
some save/restore functions, which may not actually be necessary for newer
modern GCC and clang. This appeases the in-tree gcc, though.

Test Plan

buildworld

[andrew]

You should remove crtsavres.o from gnu/lib/csu/Makefile

[andrew]

lib/csu/powerpc/crtsavres.S

9–11 ↗

(On Diff #52785)

We've been moving to the BSD 1 clause license for crt code as it tends to end up in all binaries. See lib/csu/common/crtbegin.c for an example.

[jhibbits]

Use the correct license.

[jhibbits]

lib/csu/powerpc/crtsavres.S

9–11 ↗

(On Diff #52785)

Woops, sorry. Copied the wrong license header. Fixed now.

[jhibbits]

Remove crtsavres.o from gnu/lib/csu.

[andrew]

lib/csu/powerpc64/Makefile

5 ↗

(On Diff #52799)

There's an extra space at the end of the line.