shairport-sync: needs toolchain with NPTL

Also remove the comment attributing threads dependency to alsa-lib, since
shairport-sync itself uses pthreads.

Fixes:
http://autobuild.buildroot.net/results/58e/58eafd2499919a45bfb5a2becc233d3678deedde/

Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Reviewed-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/shairport-sync/Config.in

@@ -1,7 +1,7 @@
 config BR2_PACKAGE_SHAIRPORT_SYNC
 	bool "shairport-sync"
 	depends on BR2_USE_MMU # libdaemon
-	depends on BR2_TOOLCHAIN_HAS_THREADS # alsa_lib
+	depends on BR2_TOOLCHAIN_HAS_THREADS_NPTL
 	select BR2_PACKAGE_ALSA_LIB
 	select BR2_PACKAGE_ALSA_LIB_MIXER
 	select BR2_PACKAGE_LIBDAEMON
@@ -33,6 +33,6 @@ config BR2_PACKAGE_SHAIRPORT_SYNC_LIBSOXR
 
 endif
 
-comment "shairport-sync needs a toolchain w/ threads"
+comment "shairport-sync needs a toolchain w/ NPTL"
 	depends on BR2_USE_MMU
-	depends on !BR2_TOOLCHAIN_HAS_THREADS
+	depends on !BR2_TOOLCHAIN_HAS_THREADS_NPTL