arm: add recipe for gn

This is a Google build tool used by Hafnium. It will end up in meta-oe
eventually, but until then it can live here.

Change-Id: I7a3df84624664117a6a72e2d93e86036cb483c39
Signed-off-by: Ross Burton <ross.burton@arm.com>
Signed-off-by: Jon Mason <jon.mason@arm.com>

meta-arm/recipes-devtools/gn/gn_git.bb

@@ -0,0 +1,34 @@
+SUMMARY = "GN is a meta-build system that generates build files for Ninja"
+DEPENDS += "ninja-native"
+
+LICENSE = "BSD-3-Clause"
+LIC_FILES_CHKSUM = "file://LICENSE;md5=0fca02217a5d49a14dfe2d11837bb34d"
+
+SRC_URI = "git://gn.googlesource.com/gn;protocol=https;branch=main"
+SRCREV = "69ec4fca1fa69ddadae13f9e6b7507efa0675263"
+PV = "0+git${SRCPV}"
+
+S = "${WORKDIR}/git"
+B = "${WORKDIR}/build"
+
+# TODO: os map like meson. mingw32 -> mingw
+
+do_configure[cleandirs] += "${B}"
+do_configure() {
+    python3 ${S}/build/gen.py \
+        --platform=${TARGET_OS} \
+        --host=${HOST_OS} \
+        --out-path=${B} \
+        --no-strip
+}
+
+do_compile() {
+    ninja -C ${B} --verbose
+}
+
+do_install() {
+    install -d ${D}${bindir}
+    install ${B}/gn ${D}${bindir}
+}
+
+BBCLASSEXTEND = "native nativesdk"