conf/fragments: add fragments for qemux86-64 and qemuarm64

These will be used by official bitbake-setup configurations,
and so let's start with them :) Plenty more fragments can
be added over time.

(From OE-Core rev: 872a7a89231c79afb0168e92a643aa12b9f32763)

Signed-off-by: Alexander Kanavin <alex@linutronix.de>
Signed-off-by: Mathieu Dubois-Briand <mathieu.dubois-briand@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/conf/fragments/machines/qemuarm64.conf

@@ -0,0 +1,5 @@
+BB_CONF_FRAGMENT_SUMMARY = "Use qemuarm64 as a target MACHINE, suitable for running in QEMU system emulator."
+BB_CONF_FRAGMENT_DESCRIPTION = "Select qemuarm64 as the target machine. This is the best option for running the target system inside QEMU emulator on arm64 build hosts, \
+as it allows near-native performance with kvm acceleration. Also useful for testing arm64 specific assembly code or compiler output."
+
+MACHINE ?= "qemuarm64"

meta/conf/fragments/machines/qemux86-64.conf

@@ -0,0 +1,5 @@
+BB_CONF_FRAGMENT_SUMMARY = "Use qemux86-64 as a target MACHINE, suitable for running in QEMU system emulator."
+BB_CONF_FRAGMENT_DESCRIPTION = "Select qemux86-64 as the target machine. This is the best option for running the target system inside QEMU emulator on x86-64 build hosts, \
+as it allows near-native performance with kvm acceleration. Also useful for testing x86-64 specific assembly code or compiler output."
+
+MACHINE ?= "qemux86-64"