This is a program which fixes up SDT probe relocations. It's intended for use
with the FreeBSD kernel.

It runs only on relocatable object files. For each such file specified in the
arguments, sdtpatch scans the text relocations and overwrites all calls to
DTrace probe stubs with nops. Each such relocation is recorded in a dedicated
ELF section (similar to the linker sets used to store other probe info), and
we also update the relocation so that it ends up being ignored by the linker.
In particular, this program should process all object files that are to be
linked into the kernel.

When a probe is enabled, the nops are overwritten with a call to dtrace_probe().
This is done by the kernel, using the ELF section mentioned in the paragraph
above.

Todo:
- Support cross-compilation. Some of the current uses of gelf(3) prevent this.