Always include "zlib.h" (rather than .../contrib/zlib/zlib.h)

The path to the vendored zlib is set by the build-system,
so there's no need to add additional preprocessor magic

code/AssetLib/Assbin/AssbinFileWriter.cpp

@@ -50,11 +50,7 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 #include <assimp/version.h>
 #include <assimp/IOStream.hpp>
 
-#ifdef ASSIMP_BUILD_NO_OWN_ZLIB
-#include <zlib.h>
-#else
-#include "../contrib/zlib/zlib.h"
-#endif
+#include "zlib.h"
 
 #include <ctime>
 

code/AssetLib/Q3BSP/Q3BSPFileImporter.cpp

@@ -48,11 +48,7 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 #include <assimp/DefaultLogger.hpp>
 
-#ifdef ASSIMP_BUILD_NO_OWN_ZLIB
-#include <zlib.h>
-#else
-#include "../contrib/zlib/zlib.h"
-#endif
+#include "zlib.h"
 
 #include <assimp/DefaultIOSystem.h>
 #include <assimp/StringComparison.h>

code/Common/Compression.h

@@ -41,11 +41,7 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 #pragma once
 
-#ifdef ASSIMP_BUILD_NO_OWN_ZLIB
-#   include <zlib.h>
-#else
-#   include "../contrib/zlib/zlib.h"
-#endif
+#include "zlib.h"
 
 #include <vector>
 #include <cstddef> // size_t