python_mesonpy.bbclass: move from meta-python

Move the PEP-517 back-end bbclass from meta-python to support:

[build-system]
build-backend = "mesonpy"

This is the declared backend in python3-numpy since:
942fb8caf3

(From OE-Core rev: f0d3478913b092a01eceafe0c20378cf9117f429)

Signed-off-by: Tim Orling <tim.orling@konsulko.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/classes-recipe/python_mesonpy.bbclass

@@ -0,0 +1,52 @@
+#
+# Copyright OpenEmbedded Contributors
+#
+# SPDX-License-Identifier: MIT
+#
+
+inherit meson setuptools3-base python3targetconfig python_pep517
+
+# meson_do_qa_configure does the wrong thing here because
+# mesonpy runs "meson setup ..." in do_compile context.
+# Make it a dummy function.
+meson_do_qa_configure () {
+    :
+}
+
+# This prevents the meson error:
+# ERROR: Got argument buildtype as both -Dbuildtype and --buildtype. Pick one.
+MESONOPTS:remove = "--buildtype ${MESON_BUILDTYPE}"
+
+CONFIGURE_FILES = "pyproject.toml"
+
+DEPENDS += "python3-wheel-native python3-meson-python-native"
+
+def mesonpy_get_args(d):
+    vars = ['MESONOPTS', 'MESON_CROSS_FILE', 'EXTRA_OEMESON']
+    varlist = []
+    for var in vars:
+        value = d.getVar(var)
+        vallist = value.split()
+        for elem in vallist:
+            varlist.append("-Csetup-args=" + elem)
+    return ' '.join(varlist)
+
+PEP517_BUILD_OPTS = "-Cbuilddir='${B}' ${@mesonpy_get_args(d)}"
+
+# Python pyx -> c -> so build leaves absolute build paths in the code
+INSANE_SKIP:${PN} += "buildpaths"
+INSANE_SKIP:${PN}-src += "buildpaths"
+
+python_mesonpy_do_configure () {
+    python_pep517_do_configure
+}
+
+python_mesonpy_do_compile () {
+    python_pep517_do_compile
+}
+
+python_mesonpy_do_install () {
+    python_pep517_do_install
+}
+
+EXPORT_FUNCTIONS do_configure do_compile do_install