Remove GCC version checks

Citra can't be compiled using GCC <7 because of required C++17 support, so these version checks don't need to exist anymore.

src/common/bit_field.h

@@ -195,10 +195,8 @@ private:
 };
 #pragma pack()
 
-#if (__GNUC__ >= 5) || defined(__clang__) || defined(_MSC_VER)
 static_assert(std::is_trivially_copyable<BitField<0, 1, unsigned>>::value,
               "BitField must be trivially copyable");
-#endif
 
 template <std::size_t Position, std::size_t Bits, typename T>
 using BitFieldBE = BitField<Position, Bits, T, BETag>;

src/common/swap.h

@@ -30,8 +30,8 @@
 #include <cstring>
 #include "common/common_types.h"
 
-// GCC 4.6+
-#if __GNUC__ >= 5 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 6)
+// GCC
+#ifdef __GNUC__
 
 #if __BYTE_ORDER__ && (__BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__) && !defined(COMMON_LITTLE_ENDIAN)
 #define COMMON_LITTLE_ENDIAN 1
@@ -40,7 +40,7 @@
 #endif
 
 // LLVM/clang
-#elif __clang__
+#elif defined(__clang__)
 
 #if __LITTLE_ENDIAN__ && !defined(COMMON_LITTLE_ENDIAN)
 #define COMMON_LITTLE_ENDIAN 1