rabbitmq-c: needs a toolchain with posix_spawn support

Fixes:
http://autobuild.buildroot.net/results/a6c3e79c61c5a535970d03bf37b068349f766a7f/

Signed-off-by: Joris Lijssens <joris.lijssens@gmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/rabbitmq-c/Config.in

@@ -1,6 +1,9 @@
 config BR2_PACKAGE_RABBITMQ_C
 	bool "rabbitmq-c"
 	depends on BR2_TOOLCHAIN_HAS_THREADS
+	# too old uClibc, not providing posix_spawn functions
+	# http://autobuild.buildroot.net/results/a6c3e79c61c5a535970d03bf37b068349f766a7f/
+	depends on !BR2_TOOLCHAIN_EXTERNAL_BLACKFIN_UCLINUX
 	help
 	  This is a C-language AMQP client library for use with v2.0+
 	  of the RabbitMQ broker.
@@ -9,3 +12,4 @@ config BR2_PACKAGE_RABBITMQ_C
 
 comment "rabbitmq-c needs a toolchain w/ threads"
 	depends on !BR2_TOOLCHAIN_HAS_THREADS
+	depends on !BR2_TOOLCHAIN_EXTERNAL_BLACKFIN_UCLINUX