tests: Add support for getting corefile patterns on FreeBSD

Type: improvement
Change-Id: I960edc05a9a77eb55f67cb1ec01d2b3122298ef8
Signed-off-by: Tom Jones <thj@freebsd.org>
diff --git a/test/requirements.txt b/test/requirements.txt
index beb338d..c01d311 100644
--- a/test/requirements.txt
+++ b/test/requirements.txt
@@ -23,3 +23,4 @@
 black                                   # MIT https://github.com/psf/black
 pycryptodome                            # BSD, Public Domain
 sh                                      # MIT https://github.com/amoffat/sh
+sysctl; platform_system == "FreeBSD"	# BSD