recipes: Switch away from S = WORKDIR

Where recipes use S = ${WORKDIR}, change them to set UNPACKDIR to
a subdir of WORKDIR and make S point at this instead.

I've chosen not to force S into any standard UNPACKDIR we may pick in
future just so the S = UNPACKDIR case is clearly visible by the
directory naming under WORKDIR as that should aid usability.

(From OE-Core rev: d9328e3b0b062f0621de3d114584b44f384a1c02)

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/recipes-devtools/qemu/nativesdk-qemu-helper_1.0.bb

@@ -18,7 +18,8 @@ SRC_URI = "file://${COREBASE}/scripts/runqemu \
            file://${COREBASE}/scripts/runqemu-export-rootfs \
           "
 
-S = "${WORKDIR}"
+S = "${WORKDIR}/sources"
+UNPACKDIR = "${S}"
 
 inherit nativesdk
 

meta/recipes-devtools/qemu/qemu-helper-native_1.0.bb

@@ -6,7 +6,8 @@ LIC_FILES_CHKSUM = "file://${S}/qemu-oe-bridge-helper.c;endline=4;md5=ae00a3bab8
 
 SRC_URI = "file://qemu-oe-bridge-helper.c"
 
-S = "${WORKDIR}"
+S = "${WORKDIR}/sources"
+UNPACKDIR = "${S}"
 
 inherit native
 

meta/recipes-devtools/qemu/qemuwrapper-cross_1.0.bb

@@ -2,7 +2,8 @@ SUMMARY = "QEMU wrapper script"
 HOMEPAGE = "http://qemu.org"
 LICENSE = "MIT"
 
-S = "${WORKDIR}"
+S = "${WORKDIR}/sources"
+UNPACKDIR = "${S}"
 
 DEPENDS += "qemu-native"