sz must be longer than target string

Common/ArmCPUDetect.cpp

@@ -251,7 +251,7 @@ void CPUInfo::Detect()
 	isVFP4 = true;
 #endif
 #endif // PPSSPP_PLATFORM(IOS)
-	size_t sz;
+	size_t sz = 0x41; // char brand_string[0x41]
 	if (sysctlbyname("machdep.cpu.brand_string", brand_string, &sz, nullptr, 0) != 0) {
 		strcpy(brand_string, "Unknown");
 	}