procd: extend requirejail attribute handling

e2ed964 jail: don't fail unless requirejail is set
 17e7ae7 jail: don't load libpreload-seccomp.so if it doesn't exist

Fixes openwrt/packages#11913
Signed-off-by: Daniel Golle <daniel@makrotopia.org>

package/system/procd/Makefile

@@ -12,9 +12,9 @@ PKG_RELEASE:=1
 
 PKG_SOURCE_PROTO:=git
 PKG_SOURCE_URL=$(PROJECT_GIT)/project/procd.git
-PKG_SOURCE_DATE:=2020-04-19
-PKG_SOURCE_VERSION:=d200b70e5d5b0b3b61e2573f1c2fa22b3fa9d63a
-PKG_MIRROR_HASH:=f56a7d8d74a9996fb83b6815446979550b7786019c97343fa5591d78e2b9c528
+PKG_SOURCE_DATE:=2020-04-25
+PKG_SOURCE_VERSION:=17e7ae769a4739e4b41a93f588d52cfd216b8eb2
+PKG_MIRROR_HASH:=6763cb63a53222d44be3b1ef238f3b9198d31fd533534abbbdc02202d3ef88e0
 CMAKE_INSTALL:=1
 
 PKG_LICENSE:=GPL-2.0