package/docopt-cpp: new package

Add docopt.cpp library that can be used to create intuitive command
line interfaces with very little code by describing the valid calls
using the (POSIX.1-2017) command line utility argument syntax.

Signed-off-by: Eero Aaltonen <eero.aaltonen@vaisala.com>
Reviewed-by: Angelo Compagnucci <angelo@amarulasolutions.com>
Tested-by: Angelo Compagnucci <angelo@amarulasolutions.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

package/docopt-cpp/Config.in

@@ -0,0 +1,21 @@
+config BR2_PACKAGE_DOCOPT_CPP
+	bool "docopt-cpp"
+	depends on BR2_INSTALL_LIBSTDCPP
+	depends on BR2_TOOLCHAIN_GCC_AT_LEAST_4_7 # C++11
+	help
+	  docopt is a library that lets you define a command line
+	  interface with the utility argument syntax that has been
+	  used by command line utilities for decades (POSIX.1-2017).
+	  From the description, docopt automatically generates a parser
+	  for the command line arguments.
+
+	  docopt Command-line interface description language
+	  http://docopt.org/
+
+	  docopt.cpp is a C++ port of docopt.
+
+	  https://github.com/docopt/docopt.cpp
+
+comment "docopt-cpp needs a toolchain w/ C++, gcc >= 4.7"
+	depends on !BR2_INSTALL_LIBSTDCPP || \
+		!BR2_TOOLCHAIN_GCC_AT_LEAST_4_7