azure-iot-sdk-c: Package depends on NPTL

Fixes:
http://autobuild.buildroot.org/results/1ad/1ad1c02eb866dd9a1b586308b11b4242f4321355/
http://autobuild.buildroot.org/results/fd0/fd0a1f71fec062a530bcffe95e501095657c0d50/

Signed-off-by: André Hentschel <nerv@dawncrow.de>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/azure-iot-sdk-c/Config.in

@@ -1,6 +1,7 @@
 config BR2_PACKAGE_AZURE_IOT_SDK_C
 	bool "azure-iot-sdk-c"
 	depends on BR2_INSTALL_LIBSTDCPP
+	depends on BR2_TOOLCHAIN_HAS_THREADS_NPTL
 	select BR2_PACKAGE_LIBCURL
 	select BR2_PACKAGE_LIBXML2
 	select BR2_PACKAGE_OPENSSL
@@ -12,5 +13,5 @@ config BR2_PACKAGE_AZURE_IOT_SDK_C
 
 	  https://docs.microsoft.com/nl-nl/azure/iot-hub/iot-hub-device-sdk-c-intro
 
-comment "azure-iot-sdk-c needs a toolchain w/ C++"
-	depends on !BR2_INSTALL_LIBSTDCPP
+comment "azure-iot-sdk-c needs a toolchain w/ C++ and NPTL"
+	depends on !BR2_INSTALL_LIBSTDCPP || !BR2_TOOLCHAIN_HAS_THREADS_NPTL