meta-skeleton: add recipe examples from documentation sources

This adds three examples previously located in the yocto-docs
repository (under documentation/ref-manual/examples).

The examples were not used for building the documentation
so it's better to keep them here where they can automatically be
tested.

Fixed the "hello-single" to add a version number to the .bb file.
After this, all examples build fine with the "master" branch of Poky.

Note that the "mtd-utils" example, and example of a recipe
for an Autotools page, was not copied over. It doesn't build any
more, and anyway, we already have an official recipe for a recent version
of "mtd-utils" in OE-core.

(From OE-Core rev: a186c746e431831ccbd459be2175cdaa7ed42a54)

Signed-off-by: Michael Opdenacker <michael.opdenacker@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta-skeleton/recipes-skeleton/hello-autotools/hello_2.10.bb

@@ -0,0 +1,9 @@
+DESCRIPTION = "GNU Helloworld application"
+SECTION = "examples"
+LICENSE = "GPLv3"
+LIC_FILES_CHKSUM = "file://COPYING;md5=d32239bcb673463ab874e80d47fae504"
+
+SRC_URI = "${GNU_MIRROR}/hello/hello-${PV}.tar.gz"
+SRC_URI[sha256sum] = "31e066137a962676e89f69d1b65382de95a7ef7d914b8cb956f41ea72e0f516b"
+
+inherit autotools-brokensep gettext

meta-skeleton/recipes-skeleton/hello-single/files/helloworld.c

@@ -0,0 +1,8 @@
+#include <stdio.h>
+
+int main(void)
+{
+	printf("Hello world!\n");
+
+	return 0;
+}

meta-skeleton/recipes-skeleton/hello-single/hello_1.0.bb

@@ -0,0 +1,17 @@
+DESCRIPTION = "Simple helloworld application"
+SECTION = "examples"
+LICENSE = "MIT"
+LIC_FILES_CHKSUM = "file://${COMMON_LICENSE_DIR}/MIT;md5=0835ade698e0bcf8506ecda2f7b4f302"
+
+SRC_URI = "file://helloworld.c"
+
+S = "${WORKDIR}"
+
+do_compile() {
+	${CC} ${LDFLAGS} helloworld.c -o helloworld
+}
+
+do_install() {
+	install -d ${D}${bindir}
+	install -m 0755 helloworld ${D}${bindir}
+}

meta-skeleton/recipes-skeleton/libxpm/libxpm_3.5.6.bb

@@ -0,0 +1,14 @@
+require recipes-graphics/xorg-lib/xorg-lib-common.inc
+
+DESCRIPTION = "X11 Pixmap library"
+LICENSE = "X-BSD"
+LIC_FILES_CHKSUM = "file://COPYING;md5=3e07763d16963c3af12db271a31abaa5"
+DEPENDS += "libxext"
+PR = "r2"
+PE = "1"
+
+XORG_PN = "libXpm"
+
+PACKAGES =+ "sxpm cxpm"
+FILES:cxpm = "${bindir}/cxpm"
+FILES:sxpm = "${bindir}/sxpm"