zerotier: Allow building with older GCC 4.8

ZeroTier builds fine with GCC 4.8, so relax the check to make that
possible.

Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>

net/zerotier/Makefile

@@ -7,7 +7,7 @@ include $(TOPDIR)/rules.mk
 
 PKG_NAME:=zerotier
 PKG_VERSION:=1.2.4
-PKG_RELEASE:=1
+PKG_RELEASE:=2
 
 PKG_LICENSE:=GPL-3.0
 

net/zerotier/patches/0003-gcc48.patch

@@ -0,0 +1,13 @@
+Index: ZeroTierOne-1.2.4/ext/json/json.hpp
+===================================================================
+--- ZeroTierOne-1.2.4.orig/ext/json/json.hpp
++++ ZeroTierOne-1.2.4/ext/json/json.hpp
+@@ -64,7 +64,7 @@ SOFTWARE.
+     #endif
+ #elif defined(__GNUC__)
+     #define GCC_VERSION (__GNUC__ * 10000 + __GNUC_MINOR__ * 100 + __GNUC_PATCHLEVEL__)
+-    #if GCC_VERSION < 40900
++    #if GCC_VERSION < 40800
+         #error "unsupported GCC version - see https://github.com/nlohmann/json#supported-compilers"
+     #endif
+ #endif