package/p7zip: needs __sync_*_4 intrisics

p7zip needs __sync_*_4 intrisics since its bump to version 17.04 in
commit 9332ab86f8953a8710b9377d3fba46c986610254 and
https://github.com/jinfeihan57/p7zip/commit/b0bf49e3e14ef291281b6c318c75db96c03910bc
https://github.com/jinfeihan57/p7zip/commit/6175cdaf3e762cc9e03c8af00e76ffe60d3e0844

Fixes:
 - http://autobuild.buildroot.org/results/4e1a920d09528b87803cc2e7245a470c85548946

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

package/p7zip/Config.in

@@ -1,5 +1,6 @@
 config BR2_PACKAGE_P7ZIP
 	bool "p7zip"
+	depends on BR2_TOOLCHAIN_HAS_SYNC_4 # __sync_*_4 intrisics
 	depends on BR2_INSTALL_LIBSTDCPP
 	depends on BR2_TOOLCHAIN_HAS_THREADS
 	depends on BR2_USE_WCHAR
@@ -12,4 +13,5 @@ config BR2_PACKAGE_P7ZIP
 	  http://sourceforge.net/projects/p7zip
 
 comment "p7zip needs a toolchain w/ threads, wchar, C++"
+	depends on BR2_TOOLCHAIN_HAS_SYNC_4
 	depends on !BR2_TOOLCHAIN_HAS_THREADS || !BR2_USE_WCHAR || !BR2_INSTALL_LIBSTDCPP