sysutils/dtc: Update to 1.4.6 and add test support

[kevans]

Summary

dtc 1.4.6 was released 2018/01/03 with various additional checks and bugfixes, as well as support for some syntactic sugar for overlays that allows the following:

/dts-v1/;
/plugin/;

&foo {
  status = "okay";
};

Issues addressed by the previous patches have been fixed upstream, and some work is in progress to address the two patches added here.

While here, hook up the test suite.

[manu]

Looks good to me but I'm not a port commiter.
As long as you tested a arm32 and arm64 u-boot, different arch and FreeBSD version I'm ok.

Makefile

8 ↗

(On Diff #37497)

Will it make sense to switch to uboot@ here like the u-boot ports ?

[mat]

Makefile

25–26 ↗

(On Diff #37497)

We already have BSD_INSTALL_PROGRAM, BSD_INSTALL_LIB... (look at the content of INSTALL_MACROS), you should probably use those instead of adding more.

[kevans]

Tested with: Poudriere (amd64, -HEAD; amd64, 10.3)
Tested with: u-boot-sinovoip-bpi-m3 (armv7); u-boot-pine64 (arm64)