package/espeak: add comment to ignore 'unmet dependencies'

On master 86b4eeccc4, espeak can generate spurious 'unmet dependencies'
messages:

    $ make KCONFIG_SEED=0x7A85DEE0 randconfig
    warning: (BR2_PACKAGE_ESPEAK_AUDIO_BACKEND_ALSA) selects
    BR2_PACKAGE_PORTAUDIO_CXX which has unmet directdependencies
    (BR2_PACKAGE_PORTAUDIO && BR2_INSTALL_LIBSTDCPP)

However, the dpendency chain *is* correct. There is something that
causes the kconfig parser to get really confused...

Add a comment statng the issue is spurious, so noone tries to fix it.

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Cc: Arnaud Aujon <arnaud@intelibre.fr>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/espeak/Config.in

@@ -27,6 +27,9 @@ config BR2_PACKAGE_ESPEAK_AUDIO_BACKEND_NONE
 
 config BR2_PACKAGE_ESPEAK_AUDIO_BACKEND_ALSA
 	bool "alsa via portaudio"
+	# Selecting portaudio generates spurious "unmet dependencies"
+	# warnings. Unless you are changing the dependencies of espeak
+	# or portaudio, just ignore those spurious warnings.
 	select BR2_PACKAGE_PORTAUDIO
 	select BR2_PACKAGE_PORTAUDIO_CXX