link_elf: Work around a GCC optimization bug. Fixes ddb stack traces.

Taken-from: FreeBSD r102348
kernel/bge: Fix a wrong conversion to the automatic sysctx ctx/tree setup.

Reported-by: ivadasz
kernel/bwi: Fix a wrong conversion to the automatic sysctx ctx/tree setup.

This driver isn't hooked into the build currently.

Reported-by: ivadasz