Fix FreeBSD build

Source/Core/VideoCommon/DriverDetails.cpp

@@ -30,6 +30,8 @@ namespace DriverDetails
 	const u32 m_os = OS_ALL | OS_OSX;
 #elif __linux__
 	const u32 m_os = OS_ALL | OS_LINUX;
+#elif __FreeBSD__
+	const u32 m_os = OS_ALL | OS_FREEBSD;
 #endif
 
 	static Vendor m_vendor = VENDOR_UNKNOWN;

Source/Core/VideoCommon/DriverDetails.h

@@ -14,6 +14,7 @@ namespace DriverDetails
 		OS_LINUX   = (1 << 2),
 		OS_OSX     = (1 << 3),
 		OS_ANDROID = (1 << 4),
+		OS_FREEBSD = (1 << 5),
 	};
 	// Enum of known vendors
 	// Tegra and Nvidia are separated out due to such substantial differences