pkgbase: Move headers and libs out of runtime and utilities

Headers from src/include were in the runtime-dev package but
subdirectories of src/include ended up in utilities-dev by default.
Neither package is a good choice - the headers in src/include are not
useful without the libraries contained in clibs-dev.

This moves the standard C headers to clibs-dev (C++ headers are already
in this package). While working on this, I found that various clang
libraries and headers were also bundled into utilities-dev by default
so these are also moved to clang-dev.

I also added a FreeBSD-build-essential meta package to make it simple to
install all the toolchain parts.

PR:		254173
Reviewed byb:	manu
MFC after:	1 week
Differential Revision: https://reviews.freebsd.org/D41815

include/Makefile

@@ -4,7 +4,7 @@
 
 .include <src.opts.mk>
 
-PACKAGE=runtime
+PACKAGE=clibs
 CLEANFILES= osreldate.h version
 SUBDIR= arpa protocols rpcsvc rpc xlocale
 .if ${MACHINE_CPUARCH} == "amd64"

include/Makefile.inc

@@ -0,0 +1,2 @@
+# Make sure all our subdirectory headers end up in clibs-dev
+PACKAGE=clibs

lib/clang/Makefile.inc

@@ -1,6 +1,7 @@
 
 .include <bsd.compiler.mk>
 
+PACKAGE=	clang
 MK_PIE:=	no	# Explicit libXXX.a references
 
 .if ${COMPILER_TYPE} == "clang"

lib/csu/Makefile.inc

@@ -1,3 +1,4 @@
+PACKAGE=	clibs-dev
 
 NO_WMISSING_VARIABLE_DECLARATIONS=
 # Can't instrument these files since that breaks non-sanitized programs.

lib/libclang_rt/Makefile.inc

@@ -1,6 +1,7 @@
 
 .include <bsd.compiler.mk>
 
+PACKAGE=	clang
 CRTSRC=		${SRCTOP}/contrib/llvm-project/compiler-rt
 .include "compiler-rt-vars.mk"
 

release/packages/generate-ucl.sh

@@ -44,6 +44,9 @@ main() {
 		certctl)
 			pkgdeps="caroot openssl"
 			;;
+		clang)
+			pkgdeps="lld clang-dev libcompiler_rt-dev"
+			;;
 
 		# -dev packages that have no corresponding non-dev package
 		# as a dependency.