glib: set missing cross property

GLib 2.60 onwards checks for /proc/self/cmdline instead of assuming that
it exists on Linux (because Cygwin also has it).  As this is a runtime
test it doesn't execute in cross builds so defaults to false, but under
Linux this should be true.

Restore the previous behaviour and silence the warning by setting the
cross property appropriately.

(From OE-Core rev: c308116fb7787794512c3153503ddf9da71803a8)

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

meta/recipes-core/glib-2.0/glib-2.0/glib-meson.cross

@@ -4,6 +4,7 @@ have_c99_snprintf = true
 have_unix98_printf = true
 va_val_copy = true
 growing_stack = false
+have_proc_self_cmdline = true
 
 [binaries]
 env = "/usr/bin/env"