MFC r258903,r264487,r271699,r288415:

r258903 (by markj):

Enable some previously-disabled DTrace tests for umod, ufunc and usym. They
expect the installed ksh binary to be named "ksh", which is not the case
when it's installed on FreeBSD via the shells/ksh93 port. Allow for it to be
"ksh93" as well so that the tests can actually pass.

r264487 (by markj):

Replace a few Solarisisms with their corresponding FreeBSDisms to make a few
printf tests pass.

r271699 (by markj):

Implement a workaround to allow this test program to be compiled with clang.
It seems that if a pragma is used to define a weak alias for a local
function, the pragma must appear after the function is defined.

PR: 193056

r288415 (by markj):

MFV r288408:
6266 harden dtrace_difo_chunksize() with respect to malicious DIF

illumos/illumos-gate@395c7a3dcfc66b8b671dc4b3c4a2f0ca26449922

Author: Bryan Cantrill <bryan@joyent.com>

MFC r268538:

Avoid hardcoding "gcc" in the DTrace tests.

At least one test doesn't work yet without gcc, however gcc is
not always available in base. Using the environment compiler
is more trustable and will also work with an external compiler.

Reviewed by: markj

Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

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

This test is working now, so remove it from NOTWORK.

Update for the new tests.

Sponsored by: The FreeBSD Foundation

Add the DTrace test makefile for the test suite distributed in OpenSolaris.