meson: only use lists of commands in cross file if required

There's a bug in Meson[1] where it find_program("foo") will fail if foo is
defined in the cross file as a list.

This is causing the Meson build of libdrm to fail, but for this instance we can
work around the problem by only using lists in the cross file if there are
arguments, and just using a string if there are not.

[1] mesonbuild/meson#3737

(From OE-Core rev: 928a7e26f254eb2da20bd917e83ed5467323de13)

Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/classes/meson.bbclass

@@ -42,29 +42,30 @@ MESON_CROSS_FILE_class-target = "--cross-file ${WORKDIR}/meson.cross"
 MESON_CROSS_FILE_class-nativesdk = "--cross-file ${WORKDIR}/meson.cross"
 
 def meson_array(var, d):
-    return "', '".join(d.getVar(var).split()).join(("'", "'"))
+    items = d.getVar(var).split()
+    return repr(items[0] if len(items) == 1 else items)
 
 addtask write_config before do_configure
 do_write_config[vardeps] += "MESON_C_ARGS MESON_CPP_ARGS MESON_LINK_ARGS CC CXX LD AR NM STRIP READELF"
 do_write_config() {
     # This needs to be Py to split the args into single-element lists
     cat >${WORKDIR}/meson.cross <<EOF
 [binaries]
-c = [${@meson_array('CC', d)}]
-cpp = [${@meson_array('CXX', d)}]
-ar = [${@meson_array('AR', d)}]
-nm = [${@meson_array('NM', d)}]
-ld = [${@meson_array('LD', d)}]
-strip = [${@meson_array('STRIP', d)}]
-readelf = [${@meson_array('READELF', d)}]
+c = ${@meson_array('CC', d)}
+cpp = ${@meson_array('CXX', d)}
+ar = ${@meson_array('AR', d)}
+nm = ${@meson_array('NM', d)}
+ld = ${@meson_array('LD', d)}
+strip = ${@meson_array('STRIP', d)}
+readelf = ${@meson_array('READELF', d)}
 pkgconfig = 'pkg-config'
 
 [properties]
 needs_exe_wrapper = true
-c_args = [${@meson_array('MESON_C_ARGS', d)}]
-c_link_args = [${@meson_array('MESON_LINK_ARGS', d)}]
-cpp_args = [${@meson_array('MESON_CPP_ARGS', d)}]
-cpp_link_args = [${@meson_array('MESON_LINK_ARGS', d)}]
+c_args = ${@meson_array('MESON_C_ARGS', d)}
+c_link_args = ${@meson_array('MESON_LINK_ARGS', d)}
+cpp_args = ${@meson_array('MESON_CPP_ARGS', d)}
+cpp_link_args = ${@meson_array('MESON_LINK_ARGS', d)}
 gtkdoc_exe_wrapper = '${B}/gtkdoc-qemuwrapper'
 
 [host_machine]