test(libSceAppInstUtil): use the library's public header

core/libs/tests/GuestAppInstUtil.cpp

@@ -1,15 +1,9 @@
-#include "prx/libc/include/general/VabiMacros.hpp"
+#include "prx/libSceAppInstUtil/include/Api.hpp"
 
 #include <cstdint>
 #include <cstdio>
 #include <cstdlib>
 
-extern "C" {
-int APS5_VABI sceAppInstUtilInitialize(void);
-int APS5_VABI sceAppInstUtilTerminate(void);
-int APS5_VABI sceAppInstUtilAppExists(const char* titleId, std::int32_t* exists);
-}
-
 namespace {
 
 void Require(bool condition, const char* message) {