packages: remove src from base set

The FreeBSD-src package is the largest single pkgbase package at 158M
currently. Remove it and FreeBSD-src-sys (87M) from the base set as
they are not useful to all users.

Reviewed by:	emaste, ivy
Sponsored by:	The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D52573

release/packages/sets/src.ucl

@@ -0,0 +1,5 @@
+comment = "System source code"
+
+desc = <<EOD
+This metapackage installs source code for the base system and kernel.
+EOD

release/packages/ucl/src-all.ucl

@@ -3,3 +3,7 @@ desc = <<EOD
 The source code used to rebuild the system, located in /usr/src.
 This package includes everything except the kernel source code.
 EOD
+
+annotations {
+	set = src
+}

release/packages/ucl/src-sys-all.ucl

@@ -3,3 +3,7 @@ desc = <<EOD
 The source code used to rebuild the system, located in /usr/src.
 This package includes the kernel source code.
 EOD
+
+annotations {
+	set = src
+}