package/avro-c: depends on BR2_TOOLCHAIN_HAS_SYNC_4

Fixes: http://autobuild.buildroot.net/results/989/989b4e8aaeff51bb5236c4b31e3783a0e07e4a82

Signed-off-by: Titouan Christophe <titouan.christophe@railnova.eu>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

package/avro-c/Config.in

@@ -1,9 +1,11 @@
 comment "avro-c needs a toolchain w/ dynamic library"
 	depends on BR2_STATIC_LIBS
+	depends on BR2_TOOLCHAIN_HAS_SYNC_4
 
 config BR2_PACKAGE_AVRO_C
 	bool "avro-c"
 	depends on !BR2_STATIC_LIBS  # Avro unconditionally compiles shared libs
+	depends on BR2_TOOLCHAIN_HAS_SYNC_4
 	select BR2_PACKAGE_JANSSON
 	help
 	  Select this option to install the Avro C language bindings,