Fix primitive int types on 64-bit non-Windows targets

`long` is variable-sized on non-Windows targets, so don't use it.

Added some static_asserts to confirm this is the case.

src/dusk/asserts.cpp

@@ -0,0 +1,11 @@
+#include <cstdint>
+#include <dolphin/types.h>
+
+static_assert(sizeof(u8) == sizeof(uint8_t));
+static_assert(sizeof(s8) == sizeof(int8_t));
+static_assert(sizeof(u16) == sizeof(uint16_t));
+static_assert(sizeof(s16) == sizeof(int16_t));
+static_assert(sizeof(u32) == sizeof(uint32_t));
+static_assert(sizeof(s32) == sizeof(int32_t));
+static_assert(sizeof(u64) == sizeof(uint64_t));
+static_assert(sizeof(s64) == sizeof(int64_t));