Enable to add extra single quote used by some Watcom tools.

Change-Id: I257bafd1c09c02642e0d793caf7461454bc4b04a

Revert commit: CMake: quote ':' in Windows NMake Makefiles (#9963) -- it was not the right fix and caused mucho other problemo

This converts the KWSys license to a pure 3-clause OSI-approved BSD
License.  We drop the previous license clause requiring modified
versions to be plainly marked.  We also update the KWSys copyright to
cover the full development time range.

This fixes KWSys's unix-style command-line parsing to interpret
backslash escapes inside single-quoted strings.

Add System_Parse_CommandForUnix to the KWSys System interface as a
utility to parse a unix-style command line.  Move the existing
implementation out of ProcessUNIX.  Add a flags argument reserved for
future use in providing additional behavior.

On Windows the KWSys System package generates escapes for command-line
arguments.  This fix enables quoting of the empty string as an argument.
This also adds a test to pass an empty argument to a custom command.

BUG: Fix kwsysSystem_Shell_GetArgumentForWindows to reset the windows trailing backslash count to zero when a make variable reference is encountered.

ENH: Improved escaping in kwsys/System.  Added escape of % for NMake.  Added escape of ; for the VS IDE.

ENH: Added more special unix shell characters that require quoting.  Added escaping of % as %% for shells inside mingw32-make.

ENH: Adding Shell_Flag_EchoWindows option to setup escapes for arguments to the native echo command in a shell.  This special case is needed to avoid adding quotes when passing text to echo in a native windows shell which does no command line parsing at all.

ENH: Re-implemented command line argument shell quoting to support several platforms with one code base.

BUG: Windows_ShellArgument: need to escape if the string contains one of a set of special characters as well as spaces.  Moved test for needing escapes to a separate method kwsysSystemWindowsShellArgumentNeedsEscape.

ENH: Adding 'System' component of C sources to hold system tools written in C.  Moved windows shell command line argument escaping code to kwsysSystem_Windows_ShellArgument and kwsysSystem_Windows_ShellArgumentSize.