Add sdl3_bits.odin

vendor/sdl3/sdl3_bits.odin

@@ -0,0 +1,17 @@
+package sdl3
+
+import "base:intrinsics"
+import "core:c"
+
+@(require_results)
+MostSignificantBitIndex32 :: #force_inline proc "c" (x: Uint32) -> c.int {
+	if x == 0 {
+		return -1
+	}
+	return c.int(31 - intrinsics.count_leading_zeros(x))
+}
+
+@(require_results)
+HasExactlyOneBitSet32 :: #force_inline proc "c" (x: Uint32) -> bool {
+	return x != 0 && (x & (x - 1)) == 0
+}