Update check_features.cpp - Added override for Core i7-720QM and Xeon E5520

I also get the same SSE error on a virtual machine with an Intel Xeon Processor:
The CPU of your computer (Intel(R) Xeon(R) CPU E5520 @ 2.27GHz) does not support all
features Anbox requires.
It is missing support for the following features: SSE 4.1, SSE 4.2, SSSE 3

but checking /proc/cpuinfo reveals that it supports the features:
...
model name	: Intel(R) Xeon(R) CPU E5520 @ 2.27GHz
...
flags	: fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall nx rdtscp lm constant_tsc rep_good nopl xtopology nonstop_tsc cpuid pni ssse3 sse4_1 sse4_2 x2apic hypervisor lahf_lm pti

I hope adding the following code into the array in check_features.cpp could fix the problem:
// Intel Xeon Processor E5520
"E5520"

src/anbox/cmds/check_features.cpp

@@ -38,6 +38,10 @@ std::vector<std::string> cpu_whitelist = {
   "N2840",
   // Intel Pentium T4500
   "T4500", 
+  // Intel Core i7 Q720
+  "Q 720",
+  // Intel Xeon E5520
+  "E5520"
 };
 } // namespace