ncursesada 6.4, m4_tool external (#632)

* Add Alire support for NCursesAda source version.

* Add M4 dependency.
Windows is not supported for now.

* Leave M4 definition available for all OS.

* Enable m4 package for all package managers

Co-authored-by: GHA <actions@github.com>

index/m4/m4_tool/m4_tool-external.toml

@@ -0,0 +1,13 @@
+description = "macro processor"
+name = "m4_tool"
+maintainers = ["Pascal Pignard <blady.net@orange.fr>"]
+maintainers-logins = ["Blady-Com"]
+
+[[external]]
+kind = "system"
+origin = ["m4"]
+
+[[external]]
+kind = "version-output"
+version-command = [ "m4", "--version" ]
+version-regexp = "m4.*M4. ([\\d\\.]+)"