lang/swift510: fix for building with ccache plus a couple more small changes

The attached patch includes the following changes:
     - Fix building with ccache
     - Improve readability of MAKE_JOBS_NUMBER code
     - Remove the workaround for libuuid
       After the dependency misc/e2fsprogs-libuuid was replaced with
       misc/libuuid the workaround became unnecessary
     - Bump PORTREVISION

PR:		287968
Reported by:	kib

*/e2fsprogs-lib*: switch three more users to the util-linux based ports

PR:		251489

lang/swift510: fix build on low RAM, ccache support

The port did not pass down MAKE_JOBS_NUMBER to swift's build
scripts, and Swiwt/LLVM are C++ ports and memory hungry.

Also, due to lack of CCACHE support, the port cannot pick up
where the OOM killer struck easily in, say poudriere.

Pass down --jobs ${MAKE_JOBS_NUMBER} if MAKE_JOBS_NUMBER is
defined and not empty.

While here, also support CCACHE builds so we can actually restart
in case the MAKE_JOBS_NUMBER is still too high relative to the
build host's memory.

This let me successfully build in one single attempt
with MAKE_JOBS_NUMBER=5 in /etc/make.conf on a 16 GB computer
that previously failed persistently because the port
attempted to build with all I have, meaning 16 jobs.

While here, support CCACHE build.

Approved by:	portmgr@ (blanket just-fix-it)

libxml2: chase libxml soversion bump

lang/swift510: New port

The Swift programming language -- a modern programming language with
many great features.

This port includes:
 * the Swift compiler
 * the Swift standard library
 * various tools
 * the Foundation framework
 * the Swift Package Manager (SwiftPM)
 * the run-time support that you need for running compiled programs

PR:		286454
Reviewed-by:	kib