This update brings new versions of tcl and tk, fixing
various bugs.

Tcl was updated to version 8.6.3:
* (bug)[b9e1a3] Correct Method Search Order
* (bug)[ccc2c2] Regression [lreplace {} 1 1]
* Crash regression in [oo::class destroy]
* (bug)[84af11] Regress [regsub -all {\(.*} a(b) {}]
* (bug)[cee90e] [try {} on ok {} - on return {} {}] panic
* (feature) [tcl::unsupported::getbytecode] disassember
* (enhancement) [string cat] bytecode optimization
* (bug)[82521b] segfault in mangled bytecode
* (bug)[bc5b79] Hang in some [read]s of limited size
* (bug)[bc1a96] segfault in [array set] of traced array
* (bug)[59a2e7] MSVC14 compile support
* (bug)[ed29c4] [fcopy] treats [blocked] as error
* (bug)[bf7135] regression in Tcl_Write() interface
* (bug)[10dc6d] fix [gets] on non-blocking channels
* (bug)[214cc0] Restore [lappend v] return value
* (bug)[5adc35] Stop forcing EOF to be permanent
- Add itcl-unbreak-iwidgets.patch to revert a recent change in
itcl that broke iwidgets.

- Update license tag to SPDX 1.2.

- Update to 8.6.2:
* TIP 429: New command [string cat].
* [lsearch -integer], [lsort -integer] operate on wide ints.
*** POTENTIAL INCOMPATIBILITY ***
* [dict replace], [dict remove] return canonical dicts.
*** POTENTIAL INCOMPATIBILITY ***
* Improved ::env synchronization with environment.
* transchans converted blocked writes to errors.
* [info class subclasses ::oo::object] includes ::oo::class .
* Fix: [chan configure -error] breaks [socket -async] connection.
* Better handle NUL in filenames.
* Fix: failures in nested ensemble bytecode compiler.
* Fixed crashes in...
- [apply {{} {while 1 {a {*}
[return -level 0 -code continue]}}}]
- [apply {{} {namespace upvar a b [x]}}]
- [coroutine X coroutine Y info frame]
- multi-interp font teardown
- oo chain deletion
* Plugged memory leaks in...
- execution traced coroutine deletion
- [close [zlib push ... -dictionary ...]]
- AtForkChild()
- managing oo instance lists
* Performance addressed in...
- [lappend l $multiple $arg] compile: quadratic -> linear
- binary [chan copy]: move bytes instead of copy
- Improved bytecode: [catch], [foreach], [lmap],
num. conversion
* Bytecode compiled: [concat], [linsert], [namespace origin],
[next], [nextto], [string is], [string replace],
[string tolower], [string totitle], [string toupper],
[string trim], [string trimleft],
[string trimright] [yieldto]
* New package releases:
http 2.8.8: Accept upper case schemes in URLs
tcltest 2.3.7: cleanup runs before output comparisons
platform 1.0.13: Update macosx-* variant compatibilities
TclOO 1.0.2
itcl 4.0.1
thread 2.7.1
sqlite3 3.8.6
tdbc* 1.0.1

Tk was updated to version 8.6.3:

* (bug)[9e487e] Phony button clicks from browsers to plugin
* (bug)[810c43] [text] elide changes advance epoch
* (bug)[fb35eb] fix PNG transparency appearance
* (bug)[3417012] [scale -digits $bigValue] segfault
* (bug)[3529885] [scale] handling of negative resolution
* Ocaml trouble with Tk and tailcall splice.
* Accept [image create -format PNG] (upper case).
* fix png wrong component indices
* PNG parser accept uppercase -format
* fix double free of a TkFont
* support PPM maxval up to 65535
* fix multi-interp font teardown double free
* fix option file \n syntax support
* X: correct fontconfig dependence
* fix @TK_LIBS@ in pkgconfig
* fix autoscroll initiation