Reorganize library code into libs/ (#3119)

* Reorganize files into libs/{dolphin,JSystem,PowerPC_EABI_Support,revolution,TRK_MINNOW_DOLPHIN}

* Update configure.py and project.py for new libs structure

* Refactor `#include <dolphin/x.h>` -> `<x.h>`

* Remove `__REVOLUTION_SDK__` forwards from dolphin

* Fix dolphin/ references in revolution

* Wrap `#include <dolphin.h>` in `!__REVOLUTION_SDK__`

* Always build TRK against dolphin headers

* Resolve revolution SDK header resolution issues

libs/JSystem/src/J3DU/J3DUShadow.cpp

@@ -0,0 +1,20 @@
+#include "JSystem/JSystem.h" // IWYU pragma: keep
+
+#include "JSystem/J3DU/J3DUShadow.h"
+
+#include "JSystem/JGeometry.h"
+#include "JSystem/JMath/JMath.h"
+#include "JSystem/JUtility/JUTTexture.h"
+
+void J3DUShadow_dummy(JUTTexture* tex, JGeometry::TVec3<f32>* vec) {
+    JMAAbs(0.0f);
+    JMathInlineVEC::C_VECDotProduct(NULL, NULL);
+    vec->dot(*vec);
+    vec->length();
+
+    tex->getCaptureFlag();
+    tex->getFormat();
+    JMath::fastSqrt<f32>(0.0f);
+    JUTTexture tex2;
+    tex2.setCaptureFlag(false);
+}