linuxcnc: init at 2.9.8

This adds the LinuxCNC package. The package is quite messy, as LinuxCNC
contains a mixture of GTK, TCL, QT, Python, C and C++ programs and GUI
components.

Most notably, this package has to use an opt-in impure mechanism
for setuid wrappers (using symlinks pointing out of the store into
`/run/wrappers/bin`) as LinuxCNC itself checks if the executables
in LINUXCNC_HOME are setuid wrapped. Notably, as LINUXCNC_HOME is
also used to find assets, we can not just overwrite the environment
variable for the setuid wrapper. But the check also does not verify
$0 to have setuid, but rather `$LINUXCNC_HOME/bin/rtapi_app`.
There is an environment variable supposed to override these checks
(`LINUXCNC_FORCE_REALTIME`), but it doesn't work (upstream issue:
LinuxCNC/linuxcnc#3928)

Also, the _modern_ LinuxCNC GUI (QtDragon) uses an olt qtwebkit severed
by CVEs. As a compromise, this is an opt-in feature. Use needs to
decide for themselves whether they are willing to take the risk of the
associated CVEs.

Signed-off-by: wucke13 <wucke13+github@gmail.com>

Author: wucke13

pkgs/by-name/li/linuxcnc/fix-hardcoded-executable-paths.patch

@@ -0,0 +1,26 @@
+diff --git a/tcl/bin/genedit.tcl b/tcl/bin/genedit.tcl
+index 03eed07eb0..1dd7d26544 100755
+--- a/tcl/bin/genedit.tcl
++++ b/tcl/bin/genedit.tcl
+@@ -150,7 +150,7 @@ proc geneditStart {name {ifilename "untitled.txt"} {itypes { {"All files" *} {"T
+         $menubar add cascade -label [msgcat::mc "Scripts"] -menu $scriptmenu -underline 1
+         #replaced scriptdir
+ 	#set scriptdir tcl/scripts
+-        set files [exec /bin/ls $linuxcnc::TCL_SCRIPT_DIR]
++        set files [exec ls $linuxcnc::TCL_SCRIPT_DIR]
+ 	foreach file $files {
+     	    if {[string match *.ncw $file]} {
+         	set geneditfname [file rootname $file]
+diff --git a/tcl/tklinuxcnc.tcl b/tcl/tklinuxcnc.tcl
+index d35db33840..9030ca219e 100755
+--- a/tcl/tklinuxcnc.tcl
++++ b/tcl/tklinuxcnc.tcl
+@@ -797,7 +797,7 @@ set scriptsmenu [menu $menubar.scripts -tearoff 1]
+ $menubar add cascade -label [msgcat::mc "Scripts"] -menu $scriptsmenu -underline 1
+ 
+ if { $windows == 0 } {
+-    set files [exec /bin/ls $linuxcnc::TCL_SCRIPT_DIR]
++    set files [exec ls $linuxcnc::TCL_SCRIPT_DIR]
+     foreach file $files {
+ 	if {[string match *.tcl $file]} {
+ 	    set fname [file rootname $file]